title:
Detailed Abundances for a Large Sample of Giant Stars in the Globular
  Cluster 47 Tucanae (NGC 104)

abstract:
  47 Tuc is an ideal target to study chemical evolution and GC formation in
massive more metal-rich GCs since is the closest, massive GC. We present
chemical abundances for O, Na, Al, Si, Ca, Ti, Fe, Ni, La, and Eu in 164 red
giant branch (RGB) stars in the massive globular cluster 47 Tuc using spectra
obtained with both the Hydra multi-fiber spectrograph at the Blanco 4-m
telescope and the FLAMES multi-object spectrograph at the Very Large Telescope.
We find an average [Fe/H]=--0.79$\pm$0.09 dex, consistent with literature
values, as well as over-abundances of alpha-elements
($[\alpha/\mbox{Fe}]\sim0.3$ dex). The n-capture process elements indicate that
47 Tuc is r-process dominated ([Eu/La]=+0.24), and the light elements O, Na,
and Al exhibit star-to-star variations. The Na-O anti-correlation, a signature
typically seen in Galactic globular clusters, is present in 47 Tuc, and extends
to include a small number of stars with [O/Fe] $\sim$\,--0.5. Additionally, the
[O/Na] ratios of our sample reveal that the cluster stars can be separated into
three distinct populations. A KS-test demonstrates that the O-poor/Na-rich
stars are more centrally concentrated than the O-rich/Na-poor stars. The
observed number and radial distribution of 47 Tuc's stellar populations, as
distinguished by their light element composition, agrees closely with the
results obtained from photometric data. We do not find evidence supporting a
strong Na-Al correlation in 47 Tuc, which is consistent with current models of
AGB nucleosynthesis yields.


title:
Dual Graphs and Generating Sequences of Non-divisorial Valuations on
  Two-dimensional Function Fields

abstract:
  An exposition on Spivakovsky's dual graphs of valuations on function fields
of dimension two is first given, leading to a proof of minimal generating
sequences for the non-divisorial valuations. It should be noted that the
definition of generating sequence used in this paper is different from
Spivakovsky's original usage. This change leads to an explicit formulation of
generating sequence values for the non-divisorial cases in terms of data from
their dual graphs. The proofs are elementary in the sense that only continued
fractions and the linear Diophantine Frobenius problem from classical number
theory are used.


title: Universality in the dynamics of second-order phase transitions

abstract:
  When traversing a symmetry breaking second order phase transition at a finite
rate, topological defects form whose number dependence on the quench rate is
given by simple power laws. We propose a general approach for the derivation of
such scaling laws that is based on the analytical transformation of the
associated equations of motion to a universal form rather than employing
plausible physical arguments. We demonstrate the power of this approach by
deriving the scaling of the number of topological defects in both homogenous
and non-homogenous settings. The general nature and extensions of this approach
is discussed.


title: Taming Explosive Growth through Dynamic Random Links

abstract:
  We study the dynamics of a collection of nonlinearly coupled limit cycle
oscillators, relevant to systems ranging from neuronal populations to
electrical circuits, under coupling topologies varying from a regular ring to a
random network. We find that the trajectories of this system escape to infinity
under regular coupling, for sufficiently strong coupling strengths. However,
when some fraction of the regular connections are dynamically randomized, the
unbounded growth is suppressed and the system always remains bounded. Further
we determine the critical fraction of random links necessary for successful
prevention of explosive behaviour, for different network rewiring time-scales.
These results suggest a mechanism by which blow-ups may be controlled in
extended oscillator systems.


title: Varadhan's formula, conditioned diffusions, and local volatilities

abstract:
  Motivated by marginals-mimicking results for It\^o processes via SDEs and by
their applications to volatility modeling in finance, we discuss the weak
convergence of the law of a hypoelliptic diffusions conditioned to belong to a
target affine subspace at final time, namely $\mathcal{L}(Z_t|Y_t = y)$ if
$X_{\cdot}=(Y_\cdot,Z_{\cdot})$. To do so, we revisit Varadhan-type estimates
in a small-noise regime (as opposed to small-time), studying the density of the
lower-dimensional component $Y$. The application to stochastic volatility
models include the small-time and, for certain models, the large-strike
asymptotics of the Gyongy-Dupire's local volatility function. The final product
are asymptotic formulae that can (i) motivate parameterizations of the local
volatility surface and (ii) be used to extrapolate local volatilities in a
given model.


title:
On the generating functions of a periodic infinite order linear
  recurrence

abstract:
  Let G be the space of generating functions of a periodic infinite order
linear recurrence. In this paper we provide an explicit procedure for computing
a basis of G.


title: Towards the Phenomenology of TMD Distributions at NNLL

abstract:
  We discuss the recently proposed scheme for the evolution of Transverse
Momentum Distributions using the so-called "D^R". We discuss a new method to
separate perturbative and non-perturbative effects in the analysis of the
evolution of Transverse Momentum Distributions. We argue that the scheme is
compatible with the standard CSS resummation approach when the running of the
strong coupling is taken into account properly.


title:
Graphene based Supercapacitors with Improved Specific Capacitance and
  Fast Charging Time at High Current Density

abstract:
  Graphene is a promising material for energy storage, especially for high
performance supercapacitors. For real time high power applications, it is
critical to have high specific capacitance with fast charging time at high
current density. Using a modified Hummer's method and tip sonication for
graphene synthesis, here we show graphene-based supercapacitors with high
stability and significantly-improved electrical double layer capacitance and
energy density with fast charging and discharging time at a high current
density, due to enhanced ionic electrolyte accessibility in deeper regions. The
discharge capacitance and energy density values, 195 Fg-1 and 83.4 Whkg-1, are
achieved at a current density of 2.5 Ag-1. The time required to discharge 64.18
Whkg-1 at 5 A/g is around 25 sec. At 7.5 Ag-1 current density, the cell can
deliver a specific capacitance of about 137 Fg-1 and maintain 98 % of its
initial value after 10,000 cycles, suggesting that the stable performance of
supercapacitors at high current rates is suitable for fast charging-discharging
applications. We attribute this superior performance to the highly porous
nature of graphene prepared with minimum restacking due to crimple nature
wrinkles and the improved current collecting method.


title: Optimal Cooperative Searching Using Purely Repulsive Interactions

abstract:
  Foraging, either solitarily or collectively, is a necessary behavior for
survival that is demonstrated by many organisms. Foraging can be collectively
optimized by utilizing communication between the organisms. Examples of such
communication range from high level strategic foraging by animal groups to
rudimentary signaling among unicellular organisms. Here we systematically study
the simplest form of communication via long range repulsive interactions
between two diffusing Brownian searchers on a one-dimensional lattice. We show
that the mean first passage time for either of them to reach a fixed target
depends non-monotonically on the range of the interaction and can be optimized
for a repulsive range that is comparable to the average spacing between
searchers. Our results suggest that even the most rudimentary form of
collective searching does in fact lower the search time for the foragers
suggesting robust mechanisms for search optimization in cellular communities


title: Simple Mass Matrix Ans\"atze for Neutrino Mixing

abstract:
  We estimate the PMNS (Pontecorvo-Maki-Nakagawa-Sakata) matrix in terms of
neutrino and charged lepton mixing given as $U_{\rm PMNS}=V_{\rm
lep}^\dagger(\tilde\theta_{13}) U_\nu(\tilde\theta_{23}, \tilde\theta_{12})$,
based on a new (emergent) global lepton flavor symmetry. The neutrino and
charged lepton mass matrices have simple textures. The resulting $U_{\rm PMNS}$
gives excellent agreement with experimental data (including $|U_{e3}|\simeq
0.16$).


title:
Evolution of physical observables and entropy in laser process studied
  on the basis of Kraus-form solution of laser's master equation

abstract:
  Though laser physics began at 1960s, its entropy evolution has not been
touched until very recently the Kraus-form solution of laser's master equation
is reported (Ann. Phys. 334 (2013)). We study the new physics based on the
discovery in this paper. We analyze time evolution of physical observables and
quantum optical properties in the laser process with arbitrary initial states,
such as the photon number, the second degree of coherence, etc. The evolution
of entropy of these states is also studied. Our results well conform with the
known behaviour of laser, which confirms that the master equation describes
laser suitably, and the Kraus-form operator solution is correct, elegant and
useful.


title:
Chemical peculiarities in magnetic and non-magnetic pre-main sequence A
  and B stars

abstract:
  In A- and late B-type stars, strong magnetic fields are always associated
with Ap and Bp chemical peculiarities. However, it is not clear at what point
in a star's evolution those peculiarities develop. Strong magnetic fields have
been observed in pre-main sequence A and B stars (Herbig Ae and Be stars), and
these objects have been proposed to be the progenitors of Ap and Bp stars.
However, the photospheric chemical abundances of these magnetic Herbig stars
have not been studied carefully, and furthermore the chemical abundances of
'normal' non-magnetic Herbig stars remain poorly characterized. To investigate
this issue, we have studied the photospheric compositions of 23 Herbig stars,
four of which have confirmed magnetic fields. Surprisingly, we found that half
the non-magnetic stars in our sample show lambda Bootis chemical peculiarities
to varying degrees. For the stars with detected magnetic fields, we find one
chemically normal star, one star with lambda Boo peculiarities, one star
displaying weak Ap/Bp peculiarities, and one somewhat more evolved star with
somewhat stronger Ap/Bp peculiarities. These results suggests that Ap/Bp
peculiarities are preceded by magnetic fields, and that these peculiarities
develop over the pre-main sequence lives of A and B stars. The incidence of
lambda Boo stars we find is much higher than that seen on the main sequence. We
argue that a selective accretion model for the formation of lambda Boo
peculiarities is a natural explanation for this remarkably large incidence.


title:
A four-pixel single-photon pulse-position camera fabricated from WSi
  superconducting nanowire single-photon detectors

abstract:
  We demonstrate a scalable readout scheme for an infrared single-photon
pulse-position camera consisting of WSi superconducting nanowire single-photon
detectors (SNSPDs). For an N x N array, only 2 x N wires are required to obtain
the position of a detection event. As a proof-of-principle, we show results
from a 2 x 2 array.


title: Candidate Ap stars in close binary systems

abstract:
  Short period binary systems containing magnetic Ap stars are anomalously
rare. This apparent anomaly may provide insight into the origin of the magnetic
fields in theses stars. As an early investigation of this, we observed three
close binary systems that have been proposed to host Ap stars. Two of these
systems (HD 22128 and HD 56495) we find contain Am stars, but not Ap stars.
However, for one system (HD 98088) we find the primary is indeed an Ap star,
while the secondary is an Am star. Additionally, the Ap star is tidally locked
to the secondary, and the predominately dipolar magnetic field of the Ap star
is roughly aligned with the secondary. Further investigations of HD 98088 are
planned by the BinaMIcS collaboration.


title:
Manipulate the coiling and uncoiling movements of Lepidoptera proboscis
  by its conformation optimizing

abstract:
  Many kinds of adult Lepidoptera insects possess a long proboscis which is
used to suck liquids and has the coiling and uncoiling movements. Although
experiments revealed qualitatively that the coiling movement is governed by the
hydraulic mechanism and the uncoiling movement is due to the musculature and
the elasticity, it needs a quantitative investigation to reveal how insects
achieve these behaviors accurately. Here a quasi-one-dimensional (Q1D)
curvature elastica model is proposed to reveal the mechanism of these
behaviors. We find that the functions of internal stipes muscle and basal
galeal muscle which locate at the bottom of proboscis are to adjust the initial
states in the coiling and uncoiling processes, respectively. The function of
internal galeal muscle which exists along proboscis is to adjust the line
tension. The knee bend shape is due to the local maximal spontaneous curvature
and is an advantage for nectar-feeding butterfly. When there is no knee bend,
the proboscis of fruit-piercing butterfly is easy to achieve the piercing
movement which induced by the increase of internal hydraulic pressure. All of
the results are in good agreement with experiential observation. Our study
provides a revelatory method to investigate the mechanical behaviors of other
1D biologic structures, such as proboscis of marine snail and elephant. Our
method and results are also significant in designing the bionic devices.

categories: q-bio.TO cond-mat.mtrl-sci cond-mat.soft physics.bio-ph


title: Neutral $s$ States in Loosely Bound Nuclei

abstract:
  In reviewing the data that has accumulated in light nuclei we find that the
binding energy plays a critical role in describing the variation in energy of
$s$ states relative to other states. The behavior of states with zero angular
momentum within a few MeV of threshold is qualitatively different from that of
neutron states with any other $\ell$ value or of any proton state. This
observation is explored for simple Woods-Saxon potentials and is remarkably
successful in describing a wealth of experimental data for nuclei with neutron
numbers between 5 and 10. The lingering of neutron $s$ states just below
threshold is associated with the increases in radii of the neutron density
distributions, the neutron halos, and leads to speculations about possible
halos in heavier nuclei.


title: A Study of the Unusual Z Cam Systems IW Andromedae and V513 Cassiopeia

abstract:
  The Z Cam stars IW And and V513 Cas are unusual in having outbursts following
their standstills in contrast to the usual Z Cam behavior of quiescence
following standstills. In order to gain further understanding of these
little-studied systems, we obtained spectra correlated with photometry from the
AAVSO throughout a 3-4 month interval in 2011. In addition, time-resolved
spectra were obtained in 2012 that provided orbital periods of 3.7 hrs for IW
And and 5.2 hrs for V513 Cas. The photometry of V513 Cas revealed a regular
pattern of standstills and outbursts with little time at quiescence, while IW
And underwent many excursions from quiescence to outburst to short standstills.
The spectra of IW And are similar to normal dwarf novae, with strong Balmer
emission at quiescence and absorption at outburst. In contrast, V513 Cas shows
a much flatter/redder spectrum near outburst with strong HeII emission and
prominent emission cores in the Balmer lines. Part of this continuum difference
may be due to reddening effects. While our attempts to model the outburst and
standstill states of IW And indicate a mass accretion rate near 3E-9 solar
masses per year, we could find no obvious reason why these systems behave
differently following standstill compared to normal Z Cam stars.


title: A finite chiral 4-polytope in $\mathbb{R}^4$

abstract:
  In this paper, we give an example of a chiral 4-polytope in projective
3-space. This example naturally yields a finite chiral 4-polytope in Euclidean
4-space, giving a counterexample to Theorem 11.2 of [2].


title: Single-atom quantum control of macroscopic mechanical oscillators

abstract:
  We investigate a hybrid electro-mechanical system consisting of a pair of
charged macroscopic mechanical oscillators coupled to a small ensemble of
Rydberg atoms. The resonant dipole-dipole coupling between an internal atomic
Rydberg transition and the mechanics allows cooling to its motional ground
state with a single atom despite the considerable mass imbalance between the
two subsystems. We show that the rich electronic spectrum of Rydberg atoms,
combined with their high degree of optical control, paves the way towards
implementing various quantum-control protocol for the mechanical oscillators.


title: Values of binary quadratic forms at integer points and Schmidt games

abstract:
  We prove that for any countable set $A$ of real numbers, the set of binary
indefinite quadratic forms $Q$ such that the closure of $Q(\mathbb{Z}^2)$ is
disjoint from $A$ has full Hausdorff dimension.


title:
Best approximation on semi-algebraic sets and k-border rank
  approximation of symmetric tensors

abstract:
  In the first part of this paper we study a best approximation of a vector in
Euclidean space R^n with respect to a closed semi-algebraic set C and a given
semi-algebraic norm. Assuming that the given norm and its dual norm are
differentiable we show that a best approximation is unique outside a
hypersurface. We then study the case where C is an irreducible variety and the
approximation is with respect to the Euclidean norm. We show that for a general
point in x in R^n the number of critical points of the distance function of x
to C is bounded above by a degree of a related dominant map. If C induces a
smooth projective variety in V_P in P(C^n) then this degree is the top Chern
number of a corresponding vector bundle on V_P. We then study the problem when
a best k(> 1)-border rank approximation of a symmetric tensor is symmetric. We
show that under certain dimensional conditions there exists an open
semi-algebraic set of symmetric tensors for which a best k-border rank is
unique and symmetric.


title: Stationary Markov Perfect Equilibria in Discounted Stochastic Games

abstract:
  The existence of stationary Markov perfect equilibria in stochastic games is
shown under a general condition called "(decomposable) coarser transition
kernels". This result covers various earlier existence results on correlated
equilibria, noisy stochastic games, stochastic games with finite actions and
state-independent transitions, and stochastic games with mixtures of constant
transition kernels as special cases. A remarkably simple proof is provided via
establishing a new connection between stochastic games and conditional
expectations of correspondences. New applications of stochastic games are
presented as illustrative examples, including stochastic games with endogenous
shocks and a stochastic dynamic oligopoly model.


title:
Lower bounds for the integration error for multivariate functions with
  mixed smoothness and optimal Fibonacci cubature for functions on the square

abstract:
  We prove lower bounds for the error of optimal cubature formulae for
$d$-variate functions from Besov spaces of mixed smoothness
$B^{\alpha}_{p,\theta}({\mathbb G}^d)$ in the case $0 < p, \theta \le \infty$
and $\alpha > 1/p$, where ${\mathbb G}^d$ is either the $d$-dimensional torus
${\mathbb T}^d$ or the $d$-dimensional unit cube ${\mathbb I}^d$. We prove
upper bounds for QMC methods of integration on the Fibonacci lattice for
bivariate periodic functions from $B^{\alpha}_{p,\theta}({\mathbb T}^2)$ in the
case $1\leq p \leq \infty$, $0 < \theta \leq \infty$, $\alpha>1/p$. A
non-periodic modification of this classical formula yields upper bounds for
$B^{\alpha}_{p,\theta}({\mathbb I}^2)$ if $1/p<\alpha<1+1/p$. In combination
these results yield the correct asymptotic error of optimal cubature formulae
for functions from $B^{\alpha}_{p,\theta}({\mathbb G}^2)$ and indicate that a
corresponding result is most likely also true in case $d>2$. This is compared
to the correct asymptotic of optimal cubature formulae on Smolyak grids which
results in the observation that any cubature formula on Smolyak grids is never
optimal for the general setting.


title:
Reply to Comment on "System-environment coupling derived by Maxwell's
  boundary conditions from the weak to the ultrastrong light-matter-coupling
  regime"

abstract:
  As mentioned by Simone De Liberato [arXiv:1307.5615], when we suppose the
metallic thin mirror and perform the renormalization additionally to the
approach starting from the frequently-used system-environment coupling
Hamiltonian, we can certainly resolve the discrepancy of its result from that
obtained by the reliable approach in the main discussion of our paper [Phys.
Rev. A 88, 013814 (2013), arXiv:1301.3960]. Although the suggested approach is
currently applicable to the specific situation after checking its validity by
our reliable but cumbersome approach, we instead propose to start from the
system-environment coupling Hamiltonian determined properly by the mechanism of
the confinement and loss of the cavity fields. This approach is applicable to
any cavity structures in principle, and we do not face the renormalization
problem appearing in the comment.


title:
On Maximal Ratio Diversity with Weighting Errors for Physical Layer
  Security

abstract:
  In this letter, we introduce the performance of maximal ratio combining (MRC)
with weighting errors for physical layer security. We assume both legitimate
user and eavesdropper each equipped with multiple antennas employ non ideal
MRC. The non ideal MRC is designed in terms of power correlation between the
estimated and actual fadings. We derive new closedform and generalized
expressions for secrecy outage probability. Next, we investigate the asymptotic
behavior of secrecy outage probability for high signal-to-noise ratio in the
main channel between legitimate user and transmitter. The asymptotic analysis
provides the insights about actual diversity provided by MRC with weighting
errors. We substantiate our claims with the analytic results and numerical
evaluations.


title: Quasi-exactly solvable relativistic soft-core Coulomb models

abstract:
  By considering a unified treatment, we present quasi exact polynomial
solutions to both the Klein-Gordon and Dirac equations with the family of
soft-core Coulomb potentials $V_q(r)=-Z/\left(r^q+\beta^q\right)^{1/q}$, $Z>0$,
$\beta>0$, $q\geq 1$. We consider cases $q=1$ and $q=2$ and show that both
cases are reducible to the same basic ordinary differential equation. A
systematic and closed form solution to the basic equation is obtain using the
Bethe ansatz method. For each case, the expressions for the energies and the
allowed parameters are obtained analytically and the wavefunctions are derive
in terms of the roots of a set of Bethe ansatz equations.

categories: math-ph hep-th math.CA math.MP nlin.SI quant-ph


title:
Beamforming Design for Joint Localization and Data Transmission in
  Distributed Antenna System

abstract:
  A distributed antenna system is studied whose goal is to provide data
communication and positioning functionalities to Mobile Stations (MSs). Each MS
receives data from a number of Base Stations (BSs), and uses the received
signal not only to extract the information but also to determine its location.
This is done based on Time of Arrival (TOA) or Time Difference of Arrival
(TDOA) measurements, depending on the assumed synchronization conditions. The
problem of minimizing the overall power expenditure of the BSs under data
throughput and localization accuracy requirements is formulated with respect to
the beamforming vectors used at the BSs. The analysis covers both
frequency-flat and frequency-selective channels, and accounts also for
robustness constraints in the presence of parameter uncertainty. The proposed
algorithmic solutions are based on rank-relaxation and Difference-of-Convex
(DC) programming.


title: Stability of Sequence-Based Control with Random Delays and Dropouts

abstract:
  We study networked control of non-linear systems where system states and
tentative plant input sequences are transmitted over unreliable communication
channels. The sequences are calculated recursively by using a pre-designed
nominally stabilizing state-feedback control mapping to plant state
predictions. The controller does not require receipt acknowledgments or
knowledge of delay or dropout distributions. For the i.i.d. case, in which case
the numbers of consecutive dropouts are geometrically distributed, we show how
the resulting closed loop system can be modeled as a Markov non-linear jump
system and establish sufficient conditions for stochastic stability.


title:
Detection, size, measurement and structural analysis limits for the
  2MASS, UKIDSS-LAS & VISTA VIKING surveys

abstract:
  The 2MASS, UKIDSS-LAS and VISTA VIKING surveys have all now observed the GAMA
9hr region in the $K_s$ band. Here we compare the detection rates, photometry,
basic size measurements, and single-component GALFIT structural measurements
for a sample of 37,591 galaxies. We explore the sensitivity limits where the
data agree for a variety of issues including: detection, star-galaxy
separation, photometric measurements, size and ellipticity measurements, and
S\'{e}rsic measurements. We find that 2MASS fails to detect at least 20% of the
galaxy population within all magnitude bins, however for those that are
detected we find photometry is robust ($\pm$ 0.2 mag) to 14.7 AB mag and
star-galaxy separation to 14.8 AB mag. For UKIDSS-LAS we find incompleteness
starts to enter at a flux limit of 18.9 AB mag, star-galaxy separation is
robust to 16.3 AB mag and structural measurements are robust to 17.7 AB mag.
VISTA VIKING data is complete to approximately 20.0 AB mag and structural
measurements appear robust to 18.8 AB mag.


title:
Variations of the cosmic ray composition at energy above 0.1 EeV as
  observed by muon detectors of Yakutsk array

abstract:
  The lateral distribution of muons with ~1.0x\sec(\theta) GeV in extensive air
showers within ~10^{17}-10^{19} eV energy region obtained during different
observational periods from November 1987 to June 2013 has been analyzed.
Experimental data have been compared to predictions of various hadron
interaction models. The best agreement is observed with QGSJETII-04. Until
1996, the mass composition of cosmic rays with energy below 2x10^{18} eV was
significantly lighter than in later periods.


title:
Prospects for Measuring Neutron-Star Masses and Radii with X-Ray Pulse
  Profile Modeling

abstract:
  Modeling the amplitudes and shapes of the X-ray pulsations observed from hot,
rotating neutron stars provides a direct method for measuring neutron-star
properties. This technique constitutes an important part of the science case
for the forthcoming NICER and proposed LOFT X-ray missions. In this paper, we
determine the number of distinct observables that can be derived from pulse
profile modeling and show that using only bolometric pulse profiles is
insufficient for breaking the degeneracy between inferred neutron-star radius
and mass. However, we also show that for moderately spinning (300-800 Hz)
neutron stars, analysis of pulse profiles in two different energy bands
provides additional constraints that allow a unique determination of the
neutron-star properties. Using the fractional amplitudes of the fundamental and
the second harmonic of the pulse profile in addition to the amplitude and phase
difference of the spectral color oscillations, we quantify the signal-to-noise
ratio necessary to achieve a specified measurement precision for neutron star
radius. We find that accumulating 10^6 counts in a pulse profile is sufficient
to achieve a <5% uncertainty in the neutron star radius, which is the level of
accuracy required to determine the equation of state of neutron-star matter.
Finally, we formally derive the background limits that can be tolerated in the
measurements of the various pulsation amplitudes as a function of the system
parameters.


title:
Phase Stability and Thermoelectric Properties of the Mineral FeS2: An Ab
  Initio Study

abstract:
  First principles calculations were carried out to study the phase stability
and thermoelectric properties of the naturally occurring marcasite phase of
FeS$_2$ at ambient condition as well as under pressure. Two distinct density
functional approaches has been used to investigate the above mentioned
properties. The plane wave pseudopotential approach was used to study the phase
stability and structural, elastic, and vibrational properties. The full
potential linear augment plane wave method has been used to study the
electronic structure and thermoelectric properties. From the total energy
calculations, it is clearly seen that marcasite FeS$_2$ is stable at ambient
conditions, and it undergoes a first order phase transition to pyrite FeS$_2$
at around 3.7 GPa with a volume collapse of about 3$\%$. The calculated ground
state properties such as lattice parameters, bond lengths and bulk modulus of
marcasite FeS$_2$ agree quite well with the experiment. Apart from the above
studies, phonon dispersion curves unambiguously indicate that marcasite phase
is stable under ambient conditions. Further, we do not observe any phonon
softening across the marcasite to pyrite transition and the possible reason
driving the transition is also analyzed in the present study, which has not
been attempted earlier. In addition, we have also calculated the electronic
structure and thermoelectric properties of the both marcasite and pyrite
FeS$_2$. We find a high thermopower for both the phases, especially with p-type
doping, which enables us to predict that FeS$_2$ might find promising
applications as good thermoelectric materials.


title: A Few Comments On Matlis Duality

abstract:
  For a Noetherian local ring $(R,{\mathfrak m})$ with $\mathfrak p\in
\Spec(R)$ we denote $E_R(R/\mathfrak p)$ by the $R$-injective hull of
$R/\mathfrak p$. We will show that it has an $\hat{R}^\mathfrak p$-module
structure and there is an isomorphism $E_R(R/\mathfrak p)\cong
E_{\hat{R}^\mathfrak p}(\hat{R}^\mathfrak p/\mathfrak p\hat{R}^\mathfrak p)$
where $\hat{R}^\mathfrak p$ stands for the $\mathfrak p$-adic completion of
$R$. Moreover for a complete Cohen-Macaulay ring $R$ the module
$D(E_R(R/\mathfrak p))$ is isomorphic to $\hat{R}_\mathfrak{p}$ provided that
$\dim(R/\mathfrak p)=1$ and $D(\cdot)$ denotes the Matlis dual functor
$\Hom_R(\cdot, E_R(R/\mathfrak m))$. Here $\hat{R}_\mathfrak{p}$ denotes the
completion of ${R_\mathfrak p}$ with respect to the maximal ideal $\mathfrak
pR_\mathfrak p$. These results extend those of Matlis (see \cite{m}) shown in
the case of the maximal ideal ${\mathfrak m}$.


title: Iterated trilinear Fourier integrals with arbitrary symbols

abstract:
  We prove $L^p$ estimates for trilinear multiplier operators with singular
symbols. These operators arise in the study of iterated trilinear Fourier
integrals, which are trilinear variants of the bilinear Hilbert transform.
Specifically, we consider trilinear operators determined by multipliers that
are products of two functions ${{m}}_1(\xi_1, \xi_2)$ and ${m}_2(\xi_2,
\xi_3)$, such that the singular set of $m_1$ lies in the hyperplane $
\xi_1=\xi_2$ and that of $m_2$ lies in the hyperplane $\xi_2=\xi_3$. While
previous work \cite{MTT2} requires that the multipliers satisfy $\chi_{\xi_1
<\xi_2} \cdot \chi_{\xi_2<\xi_3}$, our results allow for the case of the
arbitrary multipliers, which have common singularities.


title: Non-Gaussianity Consistency Relations, Initial States and Back-reaction

abstract:
  We explore the consistency relations for the three-point functions, in the
squeezed limit, of scalar and tensor perturbations in single-field inflation
with general initial conditions for the perturbations. For slow-roll inflation,
we find that all the three-point functions of scalar and tensor perturbations
with a coherent state as the initial state are identical to the three-point
functions with the Bunch-Davies initial state. On the other hand, there is an
apparent violation of some of the consistency relations for initial states that
are related to the Bunch-Davies state by Bogoliubov transformations and we
identify the reason for this violation. The back-reaction calculations indicate
that the three-point functions for these states can be large enough to violate
the consistency relations, however, they are too small to be observed in the
near future.


title:
An inverse boundary value problem for the magnetic Schr\"{o}dinger
  operator with a bounded magnetic potential in a slab

abstract:
  We study an inverse boundary value problem with partial data in an infinite
slab in $\mathbb{R}^{n}$, $n\geq 3$, for the magnetic Schr\"{o}dinger operator
with an $L^{\infty}$ magnetic potential and an $L^{\infty}$ electric potential.
We show that the magnetic field and the electric potential can be uniquely
determined, when the Dirichlet and Neumann data are given on either different
boundary hyperplanes or on the same boundary hyperplanes of the slab. This
generalizes the result in [11], where the same uniqueness result was
established when the magnetic potential is Lipschitz continuous. The proof is
based on the complex geometric optics solutions constructed in [14], which are
special solutions to the magnetic Schr\"{o}dinger equation with $L^{\infty}$
magnetic and electric potentials in a bounded domain.


title: $\Gamma$-unitaries, dilation and a natural example

abstract:
  This note constructs an explicit normal boundary dilation for a commuting
pair $(S,P)$ of bounded operators with the symmetrized bidisk
$$\Gamma=\{(z_1+z_2,z_1z_2):|z_1|,|z_2| \leq 1\}$$ as a spectral set. Such
explicit dilations had hitherto been constructed only in the unit disk
\cite{sfr}, the unit bidisk \cite{ando} and in the tetrablock \cite{sir and
me1}. The dilation is minimal and unique under a suitable condition. This paper
also contains a natural example of a $\Gamma$-isometry. We compute its
associated fundamental operator.


title: Phenomenology of nonperturbative charm in the nucleon

abstract:
  We perform a comprehensive analysis of the role of nonperturbative (or
intrinsic) charm in the nucleon, generated through Fock state expansions of the
nucleon wave function involving five-quark virtual states represented by
charmed mesons and baryons. We consider contributions from a variety of charmed
meson-baryon states and find surprisingly dominant effects from the (Dbar^{*0}
Lambda_c+) configuration. Particular attention is paid to the existence and
persistence of high-x structure for intrinsic charm, and the x dependence of
the c-cbar asymmetry predicted in meson-baryon models. We discuss how studies
of charmed baryons and mesons in hadronic reactions can be used to constrain
models, and outline future measurements that could further illuminate the
intrinsic charm component of the nucleon.


title: New homogeneous Einstein metrics on Stiefel manifolds

abstract:
  We consider invariant Einstein metrics on the Stiefel manifold $V_q\bb{R} ^n$
of all orthonormal $q$-frames in $\bb{R}^n$. This manifold is diffeomorphic to
the homogeneous space $\SO(n)/\SO(n-q)$ and its isotropy representation
contains equivalent summands. %This causes difficulty in the description of all
$\SO(n)$-invariant metrics.
  We prove, by assuming additional symmetries, that $V_4\bb{R}^n$ $(n\ge 6)$
admits at least four $\SO(n)$-invariant Einstein metrics, two of which are
Jensen's metrics and the other two are new metrics. Moreover, we prove that
$V_5\bb{R}^7$ admits at least six invariant Einstein metrics, two of which are
Jensen's metrics and the other four are new metrics.


title:
Beam-beam effects investigation and parameters optimization for a
  circular e+e- collider TLEP to study the Higgs boson

abstract:
  Several proposals exist for future circular electron-positron colliders
designed for precise measurements of the Higgs boson characteristics and
electroweak processes. At very high energies, synchrotron radiation of the
particles in a strong electromagnetic field of the oncoming bunch
(beamstrahlung) becomes extremely important, because of degradation of the beam
lifetime and luminosity. We present theoretical calculations of beamstrahlung
(including the beam lifetime reduction and the energy spread increase) which
are benchmarked against quasi strong-strong computer simulation. Calculation
results are used to optimize TLEP project (CERN).


title:
Complete characterization of Hadamard powers preserving Loewner
  positivity, monotonicity, and convexity

abstract:
  Entrywise powers of symmetric matrices preserving positivity, monotonicity or
convexity with respect to the Loewner ordering arise in various applications,
and have received much attention recently in the literature. Following
FitzGerald and Horn [J. Math. Anal. Appl., 1977], it is well-known that there
exists a critical exponent beyond which all entrywise powers preserve positive
definiteness. Similar phase transition phenomena have also recently been shown
by Hiai (2009) to occur for monotonicity and convexity. In this paper, we
complete the characterization of all the entrywise powers below and above the
critical exponents that are positive, monotone, or convex on the cone of
positive semidefinite matrices. We then extend the original problem by fully
classifying the positive, monotone, or convex powers in a more general setting
where additional rank constraints are imposed on the matrices. We also classify
the entrywise powers that are super/sub-additive with respect to the Loewner
ordering. Finally, we extend all the previous characterizations to matrices
with negative entries. Our analysis consequently allows us to answer a question
raised by Bhatia and Elsner (2007) regarding the smallest dimension for which
even extensions of the power functions do not preserve Loewner positivity.


title: Quantum Key Distribution From A Random Seed

abstract:
  It is designed a new quantum cryptography protocol that generates various
secret and secure keys of the same size of the transmitted qubits, implying
zero information losses between the interlocutors. Besides, generates key
swapping between the two recipients of photons, without even sharing a past
between them. This protocol differs from BB84 just in the classic procedures,
using a random seed and asymmetric cryptography.


title:
Breaking through the high redshift bottleneck of Observational Hubble
  parameter Data: The Sandage-Loeb signal Scheme

abstract:
  We propose a valid scheme to measure the Hubble parameter $H(z)$ at high
redshifts by detecting the Sandage-Loeb signal (SL signal) which can be
realized by the next generation extremely large telescope. It will largely
extend the current observational Hubble parameter data (OHD) towards the
redshift region of $z \in [2.0,5.0]$, the so-called "redshift desert", where
other dark energy probes are hard to provide useful information of the cosmic
expansion. Quantifying the ability of this future measurement by simulating
observational data for a CODEX (COsmic Dynamics and EXo-earth experiment)-like
survey and constraining various cosmological models, we find that the SL signal
scheme brings the redshift upper-limit of OHD from $z_\mathrm{max}=2.3$ to
$z_\mathrm{max}\simeq 5.0$, provides more accurate constraints on different
dark energy models, and greatly changes the degeneracy direction of the
parameters. For the $\Lambda$CDM case, the accuracy of $\Omega_m$ is improved
by $58\%$ and the degeneracy between $\Omega_m$ and $\Omega_ {\Lambda}$ is
rotated to the vertical direction of $\Omega_k = 0$ line strongly; for the
$w$CDM case, the accuracy of $w$ is improved by $15\%$. The Fisher matrix
forecast on different time-dependent $w(z)$ is also performed.


title:
Realizing three-dimensional artificial spin ice by stacking planar
  nanoarrays

abstract:
  Artificial spin ice is a frustrated magnetic two-dimensional nano-material,
recently employed to study variety of tailor-designed unusual collective
behaviours. Recently proposed extensions to three dimensions are based on
self-assembly techniques and allow little control over geometry and disorder.
We present a viable design for the realization of a three-dimensional
artificial spin ice with the same level of precision and control allowed by
lithographic nano-fabrication of the popular two-dimensional case. Our geometry
is based on layering already available two-dimensional artificial spin ice and
leads to an arrangement of ice-rule-frustrated units which is topologically
equivalent to that of the tetrahedra in a pyrochlore lattice. Consequently, we
show, it exhibits a genuine ice phase and its excitations are, as in natural
spin ice materials, magnetic monopoles interacting via Coulomb law.


title: Modulating the electronic properties of graphdiyne nanoribbons

abstract:
  By ab initio calculation, Au, Cu, Fe, Ni and Pt adatoms were proposed for
modulating the electronic property of graphdiyne naoribbons (GDNRs). GDNRs of
1~4 nm in width were found to be stable at room temperature, and the thermal
rates of Au, Cu, Fe, Ni and Pt adatoms escaping from GDNR are slower than 0.003
atoms per hour even at 900 K. According to the calculation, Au and Cu-decorated
GDNRs are metallic with carrier concentrations close to that of graphene at
room temperature, while Fe, Ni and Pt-decorated GDNRs are n-type semiconductors
with impurity states below Fermi energy. Heterojunction composed by doping Au,
Cu or Fe atom on one side of GDNR was proposed as metal-semiconductor rectifier
with rectification ratio of 2.8, 1.5 or 2.5 at 1.0 V, respectively.


title:
Second harmonic generation in a centrosymmetric gas medium with
  spatiotemporally focused intense femtosecond laser pulses

abstract:
  We demonstrate unexpectedly strong second harmonic generation (SHG) in Argon
gas by use of spatiotemporally focused (SF) femtosecond laser pulses. The
resulting SHG by the SF scheme at a 75 cm distance shows a significantly
enhanced efficiency than that achieved with conventional focusing scheme, which
offers a new promising possibility for standoff applications. Our theoretical
calculations reasonably reproduce the experimental observations, which indicate
that the observed SHG mainly originates from the gradient of nonuniform plasma
dynamically controlled by the SF laser field.


title:
Tasks and architecture of documentation subsystem in multi-level
  modeling environment MARS

abstract:
  The article describes the automated documentation system designed to generate
reports on research conducted by computer complex technical objects and systems
in multi-level modeling environment {\guillemotleft}MARS{\guillemotright}. We
defined the purposes, tasks and abilities of documentation system and examined
the types and structure of documents, and gave an example of its practical use


title: Analytical energy spectrum for hybrid mechanical systems

abstract:
  We investigate the energy spectrum for hybrid mechanical systems described by
non-parity-symmetric quantum Rabi models. A set of analytical solutions in
terms of the confluent Heun functions and their analytical energy spectrum are
obtained. The analytical energy spectrum includes regular and exceptional
parts, which are both confirmed by direct numerical simulation. The regular
part is determined by the zeros of the Wronskian for a pair of analytical
solutions. The exceptional part is relevant to the isolated exact solutions and
its energy eigenvalues are obtained by analyzing the truncation conditions for
the confluent Heun functions. By analyzing the energy eigenvalues for
exceptional points, we obtain the analytical conditions for the
energy-level-crossings, which correspond to two-fold energy degeneracy.


title: Sur la th\'eorie d'Ahlfors des surfaces

abstract: We revisit Ahlfors theory of covering surfaces thanks to Stokes theorem.


title: Gravitational Pressure and the Accelerating Universe

abstract:
  In the context of the Teleparallel Equivalent of General Relativity (TEGR)
one can obtain an alternative insight into General Relativity, as has been
shown in addressing properties as energy, momentum and angular momentum of the
gravitational field. In this paper, we apply the definition, that arises from
the field equation of the the TEGR, for the stress-energy-momentum tensor of
the gravitational field, whose spatial components naturally lead to the
definition of gravitational pressure, to compute the total space-time pressure,
due to the gravitational and matter fields, over a spherical, space-like
two-surface of a Friedman-Robertson-Walker (FRW) universe, for any curvature
index. In particular, for a spatially flat FRW universe in the actual era
(i.e., for "cold matter"), it resulted that the pressure (now due only to the
gravitational field) is outwardly directed over any spherical, spatial
two-surface. This surface can be, in particular, the apparent horizon of a
spatially flat FRW universe (in this case, the apparent horizon coincides with
the Hubble horizon). Assuming the validity of the first law of thermodynamics
for matter and gravity, and taking into account the contribution of the
gravitational field to both the energy and the pressure terms in the first law
of the (gravitational) thermodynamics, as well as considering the thermal
character of the apparent horizon of the spatially flat FRW universe, we have
thus obtained a value of the gravitational pressure that is very close to the
observed value. We interpret this result as a possibility that the accelerated
expansion of the actual universe might be due to the effect of the pressure of
the very gravitational field, instead of an totally unkown (dark) energy.


title: Stability for Time Dependent X-ray Transforms and Applications

abstract:
  We prove a logarithmic stability estimate for the time dependent X-ray
transform on $\mathbb{R}_t^+\times\mathbb{R}^n$. To do so, we extend a known
result by Begmatov for the stability of the time dependent X-ray transform in
$\mathbb{R}^+_t\times\mathbb{R}^2$. We give some examples of stability and
injectivity results in relationship to the Dirichlet-to-Neumann problem. In
particular, under the Geometric Control Condtion, we derive inverse logarithmic
stability estimates for time dependent conformal factors.


title: An Analogue of the Hilton-Milner Theorem for weak compositions

abstract:
  Let $\mathbb N_0$ be the set of non-negative integers, and let $P(n,l)$
denote the set of all weak compositions of $n$ with $l$ parts, i.e., $P(n,l)=\{
(x_1,x_2,\dots, x_l)\in\mathbb N_0^l\ :\ x_1+x_2+\cdots+x_l=n\}$. For any
element $\mathbf u=(u_1,u_2,\dots, u_l)\in P(n,l)$, denote its $i$th-coordinate
by $\mathbf u(i)$, i.e., $\mathbf u(i)=u_i$. A family $\mathcal A\subseteq
P(n,l)$ is said to be $t$-intersecting if $\vert \{ i \ :\ \mathbf u(i)=\mathbf
v(i)\} \vert\geq t$ for all $\mathbf u,\mathbf v\in \mathcal A$. A family
$\mathcal A\subseteq P(n,l)$ is said to be trivially $t$-intersecting if there
is a $t$-set $T$ of $\{1,2,\dots,l\}$ and elements $y_s\in \mathbb N_0$ ($s\in
T$) such that $\mathcal{A}= \{\mathbf u\in P(n,l)\ :\ \mathbf u(j)=y_j\ {\rm
for all}\ j\in T\}$. We prove that given any positive integers $l,t$ with
$l\geq 2t+3$, there exists a constant $n_0(l,t)$ depending only on $l$ and $t$,
such that for all $n\geq n_0(l,t)$, if $\mathcal{A} \subseteq P(n,l)$ is
non-trivially $t$-intersecting then \begin{equation} \vert \mathcal{A}
\vert\leq {n+l-t-1 \choose l-t-1}-{n-1 \choose l-t-1}+t.\notag \end{equation}
Moreover, equality holds if and only if there is a $t$-set $T$ of
$\{1,2,\dots,l\}$ such that \begin{equation} \mathcal A=\bigcup_{s\in
\{1,2,\dots, l\}\setminus T} \mathcal A_s\cup \left\{ \mathbf q_i\ :\ i\in T
\right\},\notag \end{equation} where \begin{align} \mathcal{A}_s & =\{\mathbf
u\in P(n,l)\ :\ \mathbf u(j)=0\ {\rm for all}\ j\in T\ {\rm and}\ \mathbf
u(s)=0\}\notag \end{align} and $\mathbf q_i\in P(n,l)$ with $\mathbf q_i(j)=0$
for all $j\in \{1,2,\dots, l\}\setminus \{i\}$ and $\mathbf q_i(i)=n$.


title: Quantum speedup in a memory environment

abstract:
  Memory (non-Markovian) effect is found to be able to accelerate quantum
evolution [S. Deffner and E. Lutz, Phys. Rev. Lett. 111, 010402 (2013)]. In
this work, for an atom in a structured reservoir, we show that the mechanism
for the speedup is not only related to non-Markovianity but also to the
population of excited states under a given driving time. In other words, it is
the competition between non-Markovianity and population of excited states that
ultimately determines the acceleration of quantum evolution in memory
environment. A potential experimental realization for verifying the above
phenomena is discussed by using a nitrogen-vacancy (N-V) center embedded in a
planar photonic crystal cavity (PCC) under the current experimental conditions.


title:
A generalization of the extremal function of the Davenport-Schinzel
  sequences

abstract:
  Let $[n]=\{1, \ldots, n\}$. A sequence $u=a_1a_2\dots a_l$ over $[n]$ is
called $k$-sparse if $a_i = a_j$, $i > j$ implies $i-j\geq k$. In other words,
every consecutive subsequence of $u$ of length at most $k$ does not have
letters in common. Let $u,v$ be two sequences. We say that $u$ is $v$-free, if
$u$ does not contain a subsequence isomorphic to $v$. Suppose there are only
$k$ letters appearing in $v$. The extremal function Ex$(v,n)$ is defined as the
maximum length of all the $v$-free and $k$-sparse sequences. In this paper, we
study a generalization of the extremal function Ex$(v,n)$.


title: Testing for a General Class of Functional Inequalities

abstract:
  In this paper, we propose a general method for testing inequality
restrictions on nonparametric functions. Our framework includes many
nonparametric testing problems in a unified framework, with a number of
possible applications in auction models, game theoretic models, wage
inequality, and revealed preferences. Our test involves a one-sided version of
$L_{p}$ functionals of kernel-type estimators $(1\leq p <\infty )$ and is easy
to implement in general, mainly due to its recourse to the bootstrap method.
The bootstrap procedure is based on nonparametric bootstrap applied to
kernel-based test statistics, with estimated "contact sets." We provide
regularity conditions under which the bootstrap test is asymptotically valid
uniformly over a large class of distributions, including the cases that the
limiting distribution of the test statistic is degenerate. Our bootstrap test
is shown to exhibit good power properties in Monte Carlo experiments, and we
provide a general form of the local power function. As an illustration, we
consider testing implications from auction theory, provide primitive conditions
for our test, and demonstrate its usefulness by applying our test to real data.
We supplement this example with the second empirical illustration in the
context of wage inequality.


title: Multiple periodic solutions to a discrete p(k)- Laplacian problem

abstract:
  We investigate the existence of multiple periodic solutions to the
anisotropic discrete system. We apply the linking method and a new three
critical point theorem which we provide.


title:
First integrals of ordinary difference equations beyond Lagrangian
  methods

abstract:
  A new method for finding first integrals of discrete equations is presented.
It can be used for discrete equations which do not possess a variational
(Lagrangian or Hamiltonian) formulation. The method is based on a newly
established identity which links symmetries of the underlying discrete
equations, solutions of the discrete adjoint equations and first integrals. The
method is applied to invariant mappings and discretizations of a second order
and a third order ODEs. In examples the set of independent first integrals
makes it possible to find the general solution of the discrete equations. The
method is compared to a direct method of constructing first integrals.


title: Holographic cold nuclear matter and neutron star

abstract:
  We have previously found a new phase of cold nuclear matter based on a
holographic gauge theory, where baryons are introduced as instanton gas in the
probe D8/$\overline{\rm D8}$ branes. In our model, we could obtain the equation
of state (EOS) of our nuclear matter by introducing fermi momentum. Then, here
we apply this model to the neutron star and study its mass and radius by
solving the Tolman-Oppenheimer-Volkoff (TOV) equations in terms of the EOS
given here. We give some comments for our holographic model from a viewpoint of
the other field theoretical approaches.


title: CMB anomalies from an inflationary model in string theory

abstract:
  Recent Planck measurements show some CMB anomalies on large angular scales,
which confirms the early observations by WMAP. We show that an inflationary
model, in which before the slow-roll inflation the Universe is in a
superinflationary phase, can generate a large-scale cutoff in the primordial
power spectrum, which may account for not only the power suppression on large
angular scales, but also a large dipole power asymmetry in the CMB. We discuss
an implementation of our model in string theory.


title:
Distinguishing between inhomogeneous model and $\Lambda\textrm{CDM}$
  model with the cosmic age method

abstract:
  Cosmological observables could be used to construct cosmological models,
however, a fixed number of observables limited on the light cone is not enough
to uniquely determine a certain model. A reconstructed spherically symmetric,
inhomogeneous model that share the same angular-diameter-distance-redshift
relationship $d_A(z)$ and Hubble parameter $H(z)$ besides $\Lambda\textrm{CDM}$
model (which we call LTB-$\Lambda\textrm{CDM}$ model in this paper), may
provide another solution. Cosmic age, which is off the light cone, could be
employed to distinguish these two models. We derive the formulae for age
calculation with origin conditions. From the data given by 9-year WMAP
measurement, we compute the likelihood of the parameters in these two models
respectively by using the Distance Prior method and do likelihood analysis by
generating Monte Carlo Markov Chain for the purpose of breaking the degeneracy
of $\Omega_m$ and $H_0$ (the parameters that we use for calculation). The
results yield to be: $t_{\Lambda\textrm{CDM}} =13.76 \pm 0.09 ~\rm Gyr$,
$t_{\rm {LTB}-\Lambda\textrm{CDM}} =11.38 \pm 0.15 ~\rm Gyr$, both in $1\sigma$
agreement with the constraint of cosmic age given by metal-deficient stars. The
cosmic age method that is set in this paper enables us to distinguish between
the inhomogeneous model and $\Lambda\textrm{CDM}$ model.


title: Higgs Production in Two-Photon Process and Transition Form Factor

abstract:
  The Higgs production in the two-photon fusion process is investigated where
one of the photons is off-shell while the other one is on-shell. This process
is realized in either electron-positron collision or electron-photon collision
where the scattered electron or positron is detected (single tagging) and
described by the transition form factor. We calculate the contributions to the
transition form factor of the Higgs boson coming from top-quark loops and
W-boson loops. We then study the $Q^2$ dependence of each contribution to the
total transition form factor and also of the differential cross section for the
Higgs production.


title: Polsat: A Portfolio LTL Satisfiability Solver

abstract:
  In this paper we present a portfolio LTL-satisfiability solver, called
Polsat. To achieve fast satisfiability checking for LTL formulas, the tool
integrates four representative LTL solvers: pltl, TRP++, NuSMV, and Aalta. The
idea of Polsat is to run the component solvers in parallel to get best overall
performance; once one of the solvers terminates, it stops all other solvers.
Remarkably, the Polsat solver utilizes the power of modern multi-core compute
clusters. The empirical experiments show that Polsat takes advantages of it.
Further, Polsat is also a testing plat- form for all LTL solvers.


title:
On the interpretation of negative birefringence observed in strong-field
  optical pump-probe experiments: high-order Kerr and plasma grating effects

abstract:
  The analysis of negative birefringence optically induced in major air
components (Loriot et al., [1, 2]) is revisited in light of the recently
reported plasma grating-induced phase-shift effect predicted for strong field
pump-probe experiments (Wahlstrand and Milchberg, [3]). The nonlinear birefrin-
gence induced by a short and intense laser pulse in argon is measured by
femtosecond time-resolved polarimetry. The experiments are performed with
degenerate colors, where the pump and probe beam share the same spectrum, or
with two different colors and non-overlapping spectra. The in- terpretation of
the experimental results is substantiated using a numerical 3D+1 model
accounting for nonlinear propagation effects, cross-beam geometry of the
interacting laser pulses, and detec- tion technique. The model also includes
the ionization rate of argon and high-order Kerr indices introduced by Loriot
et al. enabling to assess the contribution of both terms to the observed
effect. The results show that the ionization-induced phase-shift has a minor
contribution compared to the high-order Kerr effect formerly introduced, the
latter allowing a reasonably good reproduction of the experimental data for the
present conditions.


title:
Two-species hard-core bosons on the triangular lattice: A quantum Monte
  Carlo study

abstract:
  Using worm-type quantum Monte Carlo simulations, we investigate bosonic
mixtures on the triangular lattice of two species of bosons, which interact via
nearest-neighbour intraspecies ($V$) and onsite interspecies ($U$) repulsions.
For the case of symmetric hopping amplitude ($t_A/V=t_B/V$) and $U/V=1$, we
determine a rich ground-state phase diagram that contains double solid, double
superfluid (2SF), supersolid (SS), solid-superfluid (Solid-SF) and counterflow
supersolid (CSS) states. The SS, Solid-SF and CSS states exhibit spontaneous
symmetry breaking among the three sublattices of the triangular lattice and
between the two species, which leads to nonzero crystalline density wave order
in each species. We furthermore show that the CSS and the SS states are present
for $t_A/V \neq t_B/V$, and the latter even survives up to $t_A/V \rightarrow
\infty$ or $t_B/V \rightarrow \infty$ limit. The effects induced by the
variation of $U/V$ and by the imbalance of particle numbers of the two species
are also explored.


title: Proposal for a Graphene Plasmonic THz Emitter

abstract:
  We propose a terahertz radiation source based on the excitation of plasma
resonances in graphene structures by means of mixing two NIR laser signals with
a THz difference frequency. The process is the photo-thermo-electric effect
which has recently been demonstrated to be operative at THz frequencies in
graphene. An antenna couples the THz radiation out of the sub-wavelength
graphene element and into the far field. The emission is monochromatic with a
bandwidth determined by that of the NIR laser sources. The output power of the
device as a function of the emitter frequency is estimated at tens of
microWatts.


title: Depth and the local Langlands correspondence

abstract:
  Let G be an inner form of a general linear group over a non-archimedean local
field. We prove that the local Langlands correspondence for G preserves depths.
We also show that the local Langlands correspondence for inner forms of special
linear groups preserves the depths of essentially tame Langlands parameters.


title:
Production of heavy meson pairs in $p\bar{p}$ collisions within a double
  handbag approach

abstract:
  We study the pair-production of heavy mesons in proton-antiproton
annihilations within a perturbative QCD-motivated framework. In particular we
investigate $p \bar{p} \rightarrow \overline{D^0} D^0$ within a double handbag
approach, where a hard subprocess factorizes from soft hadronic matrix
elements. The soft matrix elements can be parametrized by transition
distribution amplitudes, which are off-diagonal in flavor space. The transition
distribution amplitudes are modelled as overlaps of light-cone wave functions.
We obtain rather robust model results for $p \bar{p} \rightarrow \overline{D^0}
D^0$ cross sections, which are expected to be measured at the future
$\bar{\text{P}}\text{ANDA}$ detector at GSI-FAIR.


title: On the Reality of Unruh Temperature

abstract:
  In contrast to recent criticism we undertake to show that the notion of Unruh
temperature describes a real thermal property of the vacuum if viewed from an
accelerated reference frame. We embed our investigation in a more general
analysis of general relativistic temperature (Tolman-Ehrenfest effect) with the
entropy-maximum principle being our guiding principle. We show that the Unruh
effect neatly fits into this more general framework. Our criterion of reality
is, first, the possibility to transfer a quantum of acceleration radiation to
the inertial laboratory where it can be studied in principle under ordinary
thrmodynamical conditions. Second, we emphasize as another criterion the
importance of the coincidence of the accelerated and inertial observer
description as far as the final objective result is concerned.


title: Rigidity at infinity of trees and Euclidean buildings

abstract:
  We show that if a group G acts isometrically on a locally finite leafless
R-tree inducing a two-transitive action on its ends, then this tree is
determined by the action of G on the boundary. As a corollary we obtain that
locally finite Euclidean buildings without tree or cone factors are determined
by their complete building at infinity.


title: Decentralized Dynamics for Finite Opinion Games

abstract:
  Game theory studies situations in which strategic players can modify the
state of a given system, due to the absence of a central authority. Solution
concepts, such as Nash equilibrium, are defined to predict the outcome of such
situations. In multi-player settings, it has been pointed out that to be
realistic, a solution concept should be obtainable via processes that are
decentralized and reasonably simple. Accordingly we look at the computation of
solution concepts by means of decentralized dynamics. These are algorithms in
which players move in turns to improve their own utility and the hope is that
the system reaches an "equilibrium" quickly.
  We study these dynamics for the class of opinion games, recently introduced
by Bindel et al. [Bindel et al., FOCS2011]. These are games, important in
economics and sociology, that model the formation of an opinion in a social
network. We study best-response dynamics and show upper and lower bounds on the
convergence to Nash equilibria. We also study a noisy version of best-response
dynamics, called logit dynamics, and prove a host of results about its
convergence rate as the noise in the system varies. To get these results, we
use a variety of techniques developed to bound the mixing time of Markov
chains, including coupling, spectral characterizations and bottleneck ratio.


title:
A Universal Power-law Profile of Pseudo-Phase-Space Density-like
  Quantities in Elliptical Galaxies

abstract:
  We study profiles of mass density, velocity dispersion (VD), and their
combination using $\sim 2000$ nearly spherical and rotation-free SDSS galaxies.
For observational stellar mass density $\rho_{\star}(r)$ we consider a range of
dark matter (DM) distribution $\rho_{\rm{DM}}(r)$ and VD anisotropy $\beta(r)$
to investigate radial stellar VD $\sigma_{\rm\star r}(r)$ using the spherical
Jeans equation. While mass and VD profiles vary appreciably depending on DM
distribution and anisotropy, the pseudo-phase-space density-like combination
$\rho(r)/\sigma_{\rm\star r}^3(r)$ with total density $\rho(r)=
\rho_{\star}(r)+\rho_{\rm{DM}}(r)$ is nearly universal. In the optical region
the minus of its logarithmic slope has a mean value of
$\langle\chi\rangle\approx 1.86$--$1.90$ with a galaxy-to-galaxy rms scatter of
$\approx 0.04$--$0.06$, which is a few times smaller than that of $\rho(r)$
profiles. The scatter of $\chi$ can be increased by invoking wildly varying
anisotropies that are, however, less likely because they would produce too
large a scatter of line-of-sight VD profiles. As an independent check of this
universality we analyze stellar orbit-based dynamical models of 15 ETGs of Coma
cluster provided by J. Thomas. Coma ETGs, with $\sigma_{\star\rm{r}}(r)$
replaced by the rms velocity of stars $v_{\star\rm{rms}}(r)$ including net
rotation, exhibit a similar universality with a slope of $\chi= 1.93\pm 0.06$.
Remarkably, the inferred values of $\chi$ for ETGs match well the slope
$\approx 1.9$ predicted by N-body simulations of DM halos. We argue that the
inferred universal nature of $\rho(r)/\sigma_{\rm\star r}^3(r)$ cannot be fully
explained by equilibrium alone, implying that some astrophysical factors
conspire and/or it reflects a fundamental principle in collisionless formation
processes.


title: Linear Extensions of N-free Orders

abstract:
  We consider the number of linear extensions of an N-free order P. We give
upper and lower bounds on this number in terms of parameters of the
corresponding arc diagram. We propose a dynamic programming algorithm to
calculate the number. The algorithm is polynomial if a new parameter called
activity is bounded by a constant. The activity can be bounded in terms of
parameters of the arc diagram.


title:
Crystallized and amorphous vortices in rotating atomic-molecular
  Bose-Einstein condensates

abstract:
  Vortex is a topological defect with a quantized winding number of the phase
in superfluids and superconductors. Here, we investigate the crystallized
(triangular, square, honeycomb) and amorphous vortices in rotating
atomic-molecular Bose-Einstein condensates (BECs) by using the damped projected
Gross-Pitaevskii equation. The amorphous vortices are the result of the
considerable deviation induced by the interaction of atomic-molecular vortices.
By changing the atom-molecule interaction from attractive to repulsive, the
configuration of vortices can change from an overlapped atomic-molecular
vortices to carbon-dioxide-type ones, then to atomic vortices with interstitial
molecular vortices, and finally into independent separated ones. The Raman
detuning can tune the ratio of the atomic vortex to the molecular vortex. We
provide a phase diagram of vortices in rotating atomic-molecular BECs as a
function of Raman detuning and the strength of atom-molecule interaction.


title:
The Effect of Large-Scale Structure on the Magnification of
  High-Redshift Sources by Cluster-Lenses

abstract:
  Cluster gravitational lensing surveys like the Hubble Space Telescope
Frontier Fields survey will detect distant galaxies 10-50 times fainter than
any yet discovered. Using these surveys to measure the luminosity function of
such faint, distant galaxies, however, requires that magnification maps built
from the constraints of strongly-lensed images be accurate. For models that
assume the cluster and nearby (correlated) structures are the only significant
sources of lensing, a potential source of error in these maps comes from the
fact that light rays also suffer weak deflections by uncorrelated large-scale
structure along the line-of-sight, i.e. cosmic weak lensing (CWL). To
demonstrate the magnitude of this effect, we calculate the magnification change
which results when the same cluster-lens is placed along different lines of
sight. Using a simple density profile for a cluster-lens at z~0.3-0.5 and the
power spectrum of the matter density fluctuations responsible for CWL, we show
that the typical magnifications of ~5(10) of sources at z=6-10 can differ by
~10-20(20-30)% from one line-of-sight to another. However, these fluctuations
rise to greater than order unity near critical curves, indicating that CWL
tends to make its greatest contribution to the most magnified images. We
conclude that the neglect of CWL in determining the intrinsic luminosities of
highly-magnified galaxies may introduce errors significant enough to warrant
further effort to include this contribution in cluster-lens modeling. We
suggest that methods of modeling CWL in galaxy-strong-lensing systems should be
generalized to cluster-lensing systems.


title:
Periodicity in Class II methanol masers in high mass star forming
  regions

abstract:
  We report the results of 10 years of monitoring of six regularly varying 6.7
GHz methanol masers using the Hartebeesthoek 26m telescope. Observations were
done at intervals of 1--2 weeks, with faster sampling during flaring episodes.
Four of the sources were also monitored at 12.2 GHz and show correlated
variations. We find the Lomb-Scargle periodogram to be the most sensitive
method to search for periodicity but possibly prone to false detections.
Periods range from 132.8 days (with 26 cycles observed) to 509 days (with 7
cycles observed). Five of the sources show arguably periodic variations, while
G331.13-0.24 shows strong periodicity in one peak, with large and variable
delays in other peaks.


title:
Hardness Amplification and the Approximate Degree of Constant-Depth
  Circuits

abstract:
  We establish a generic form of hardness amplification for the approximability
of constant-depth Boolean circuits by polynomials. Specifically, we show that
if a Boolean circuit cannot be pointwise approximated by low-degree polynomials
to within constant error in a certain one-sided sense, then an OR of disjoint
copies of that circuit cannot be pointwise approximated even with very high
error. As our main application, we show that for every sequence of degrees
$d(n)$, there is an explicit depth-three circuit $F: \{-1,1\}^n \to \{-1,1\}$
of polynomial-size such that any degree-$d$ polynomial cannot pointwise
approximate $F$ to error better than
$1-\exp\left(-\tilde{\Omega}(nd^{-3/2})\right)$. As a consequence of our main
result, we obtain an $\exp\left(-\tilde{\Omega}(n^{2/5})\right)$ upper bound on
the the discrepancy of a function in AC$^0$, and an
$\exp\left(\tilde{\Omega}(n^{2/5})\right)$ lower bound on the threshold weight
of AC$^0$, improving over the previous best results of
$\exp\left(-\Omega(n^{1/3})\right)$ and $\exp\left(\Omega(n^{1/3})\right)$
respectively.
  Our techniques also yield a new lower bound of
$\Omega\left(n^{1/2}/\log^{(d-2)/2}(n)\right)$ on the approximate degree of the
AND-OR tree of depth $d$, which is tight up to polylogarithmic factors for any
constant $d$, as well as new bounds for read-once DNF formulas. In turn, these
results imply new lower bounds on the communication and circuit complexity of
these classes, and demonstrate strong limitations on existing PAC learning
algorithms.


title: Multiscale and multimodel simulation of Bloch point dynamics

abstract:
  We present simulation results on the structure and dynamics of micromagnetic
point singularities with atomistic resolution. This is achieved by embedding an
atomistic computational region into a standard micromagnetic algorithm. Several
length scales are bridged by means of an adaptive mesh refinement and a
seamless coupling between the continuum theory and a Heisenberg formulation for
the atomistic region. The code operates on graphical processing units and is
able to detect and track the position of strongly inhomogeneous magnetic
regions. This enables us to reliably simulate the dynamics of Bloch points,
which means that a fundamental class of micromagnetic switching processes can
be analyzed with unprecedented accuracy. We test the code by comparing it with
established results and present its functionality with the example of a
simulated field-driven Bloch point motion in a soft-magnetic cylinder.


title:
Experiences and Insights from Applying GQM+Strategies in a Systems
  Product Development Organisation

abstract:
  Aligning software-related activities with corporate strategies and goals is
increasingly important for several reasons such as increasing the customer
satisfaction in software-based products and services. Several approaches have
been proposed to create such an alignment. GQM+Strategies is an approach that
applies measurement principles to link goals and strategies on different levels
of an organisation. In this paper, we describe experiences from applying
GQM+Strategies to elicit, link, and align the goals of an integrated systems
product development organisation across multiple organisational levels. We
provide insights into how GQM+Strategies was applied during a five- month
period. The paper presents the enacted application process and main lessons
learnt. In addition, related approaches are described and an outlook on future
work is given.


title:
Transfer Matrices as Non-Unitary S-Matrices, Multimode Unidirectional
  Invisibility, and Perturbative Inverse Scattering

abstract:
  We show that in one dimension the transfer matrix M of any scattering
potential v coincides with the S-matrix of an associated time-dependent
non-Hermitian 2 x 2 matrix Hamiltonian H(\tau). If v is real-valued, H(\tau) is
pseudo-Hermitian and its exceptional points correspond to the classical turning
points of v. Applying time-dependent perturbation theory to H(\tau) we obtain a
perturbative series expansion for M and use it to study the phenomenon of
unidirectional invisibility. In particular, we establish the possibility of
having multimode unidirectional invisibility with wavelength-dependent
direction of invisibility and construct various physically realizable optical
potentials possessing this property. We also offer a simple demonstration of
the fact that the off-diagonal entries of the first Born approximation for M
determine the form of the potential. This gives rise to a perturbative inverse
scattering scheme that is particularly suitable for optical design. As a simple
application of this scheme, we construct an infinite-range unidirectionally
invisible potential.

categories: quant-ph cond-mat.other hep-th math-ph math.MP physics.optics


title: Coupling independent walkers and the inclusion process

abstract:
  We show propagation of local equilibrium for the symmetric inclusion process
(SIP) after diffusive rescaling of space and time, as well as the local
equilibrium property of the non-equilibrium steady state in the boundary driven
SIP. The main tool is self-duality and a coupling between $n$ SIP particles and
$n$ independent random walkers.


title: $J/\psi$ polarization in p+p collisions at $\sqrt{s}$ = 200 GeV in STAR

abstract:
  We report on a polarization measurement of inclusive $J/\psi$ mesons in the
di-electron decay channel at mid-rapidity at 2 $<p_{T}<$ 6 GeV/$c$ in $p+p$
collisions at $\sqrt{s}$ = 200 GeV. Data were taken with the STAR detector at
RHIC. The $J/\psi$ polarization measurement should help to distinguish between
different models of the $J/\psi$ production mechanism since they predict
different $p_{T}$ dependences of the $J/\psi$ polarization. In this analysis,
$J/\psi$ polarization is studied in the helicity frame. The polarization
parameter $\lambda_{\theta}$ measured at RHIC becomes smaller towards high
$p_{T}$, indicating more longitudinal $J/\psi$ polarization as $p_{T}$
increases. The result is compared with predictions of presently available
models.


title:
Efficient experimental validation of photonic boson sampling against the
  uniform distribution

abstract:
  A boson sampling device is a specialised quantum computer that solves a
problem which is strongly believed to be computationally hard for classical
computers. Recently a number of small-scale implementations have been reported,
all based on multi-photon interference in multimode interferometers. In the
hard-to-simulate regime, even validating the device's functioning may pose a
problem . In a recent paper, Gogolin et al. showed that so-called symmetric
algorithms would be unable to distinguish the experimental distribution from
the trivial, uniform distribution. Here we report new boson sampling
experiments on larger photonic chips, and analyse the data using a scalable
statistical test recently proposed by Aaronson and Arkhipov. We show the test
successfully validates small experimental data samples against the hypothesis
that they are uniformly distributed. We also show how to discriminate data
arising from either indistinguishable or distinguishable photons. Our results
pave the way towards larger boson sampling experiments whose functioning,
despite being non-trivial to simulate, can be certified against alternative
hypotheses.


title: Anomalies in bulk supercooled water at negative pressure

abstract:
  Water is the most familiar liquid, and arguably the most complex. Anomalies
of supercooled water have been measured during decades, and competing
interpretations proposed. Yet, a decisive experiment remains elusive, because
of unavoidable crystallization into ice. We investigate the state of water that
is both supercooled and under mechanical tension, or negative pressure. Liquids
under negative pressure can be found in plants or fluid inclusions in minerals.
Using such water inclusions in quartz, we report the first measurements on
doubly metastable water down to $-15^\circ\mathrm{C}$ and around
$-100\,\mathrm{MPa}$. We observe sound velocity anomalies that can be
reproduced quantitatively with molecular dynamics simulations. These results
rule out one proposed scenario for water anomalies, and put further constraints
on the remaining ones.


title: Transgression field theory at the interface of topological insulators

abstract:
  Topological phases of matter can be classified by using Clifford algebras
through Bott periodicity. We consider effective topological field theories of
quantum Hall systems and topological insulators that are Chern-Simons and BF
field theories. The edge states of these systems are related to the gauge
invariance of the effective actions. For the edge states at the interface of
two topological insulators, transgression field theory is proposed as a gauge
invariant effective action. Transgression actions of Chern-Simons theories for
(2+1)D and (4+1)D and BF theories for (3+1)D are constructed. By using
transgression actions, the edge states are written in terms of the bulk
connections of effective Chern-Simons and BF theories.


title: Linear Toric Fibrations

abstract:
  These notes are based on three lectures given at the 2013 CIME/CIRM summer
school. The purpose of this series of lectures is to introduce the notion of a
toric fibration and to give its geometrical and combinatorial
characterizations. Polarized toric varieties which are birationally equivalent
to projective toric bundles are associated to a class of polytopes called
Cayley polytopes. Their geometry and combinatorics have a fruitful interplay
leading to fundamental insight in both directions. These notes will illustrate
geometrical phenomena, in algebraic geometry and neighboring fields, which are
characterized by a Cayley structure. Examples are projective duality of toric
varieties and polyhedral adjunction theory.


title:
Trade-offs Computing Minimum Hub Cover toward Optimized Graph Query
  Processing

abstract:
  As techniques for graph query processing mature, the need for optimization is
increasingly becoming an imperative. Indices are one of the key ingredients
toward efficient query processing strategies via cost-based optimization. Due
to the apparent absence of a common representation model, it is difficult to
make a focused effort toward developing access structures, metrics to evaluate
query costs, and choose alternatives. In this context, recent interests in
covering-based graph matching appears to be a promising direction of research.
In this paper, our goal is to formally introduce a new graph representation
model, called Minimum Hub Cover, and demonstrate that this representation
offers interesting strategic advantages, facilitates construction of candidate
graphs from graph fragments, and helps leverage indices in novel ways for query
optimization. However, similar to other covering problems, minimum hub cover is
NP-hard, and thus is a natural candidate for optimization. We claim that
computing the minimum hub cover leads to substantial cost reduction for graph
query processing. We present a computational characterization of minimum hub
cover based on integer programming to substantiate our claim and investigate
its computational cost on various graph types.


title: Giant monopoles as a dark matter candidate

abstract:
  The most prominent successes of weakly interacting massive particle (WIMP)
models of dark matter are at comoving scales of megaparsecs. At kiloparsec
scales they face challenges in explaining the density profiles, abundances and
phase space distributions of satellite galaxies in our local group. An
alternate dark matter candidate, the giant 't Hooft-Polyakov monopole, is
proposed which may share the large distance successes of WIMPs while evading
their short distance problems. These are classical field theory solutions of a
dark sector including a nonabelian gauge field, an adjoint scalar field and
fundamental fermions. In such models each halo consists of a single monopole
characterized by a conserved integer charge.


title:
Electrical Characterization of a Thin Edgeless N-on-p Planar Pixel
  Sensors For ATLAS Upgrades

abstract:
  In view of the LHC upgrade phases towards the High Luminosity LHC (HL-LHC),
the ATLAS experiment plans to upgrade the Inner Detector with an all-silicon
system. Because of its radiation hardness and cost effectiveness, the n-on-p
silicon technology is a promising candidate for a large area pixel detector.
The paper reports on the joint development, by LPNHE and FBK of novel n-on-p
edgeless planar pixel sensors, making use of the active trench concept for the
reduction of the dead area at the periphery of the device. After discussing the
sensor technology, and presenting some sensors' simulation results, a complete
overview of the electrical characterization of the produced devices will be
given.


title:
Measurement and modeling of the nonlinearity of photovoltaic and
  Geiger-mode photodiodes

abstract:
  While in most cases the absolute accuracy, resolution, and noise floor are
the only relevant specifications for the dynamic range of a photodetector,
there are experiments for which the linearity plays a more important role than
the former three properties. In these experiments nonlinearity can lead to
systematic errors. In our work we present a modern implementation of the
well-known superposition method and apply it to two different types of
photodetectors.


title:
Iterative Determination of Distributions by the Monte Carlo Method in
  Problems with an External Source

abstract:
  In the Monte Carlo (MC) method statistical noise is usually present.
Statistical noise may become dominant in the calculation of a distribution,
usually by iteration, but is less Important in calculating integrals. The
subject of the present work is the role of statistical noise in iterations
involving stochastic simulation (MC method). Convergence is checked by
comparing two consecutive solutions in the iteration. The statistical noise may
randomize or pervert the convergence. We study the probability of the
convergence, and the correct estimation of the variance in a simplified model
problem. We study the statistical properties of the solution to a deterministic
problem with a stochastic source obtained from a stochastic calculation. There
are iteration strategies resulting in non-convergence, or randomly stopped
iteration.


title: Towards thermodynamics with $N_f=2+1+1$ twisted mass quarks

abstract:
  We present preliminary results achieved within a recently started project
dealing with QCD thermodynamics in the presence of a fully dynamical second
quark family. We are employing the Wilson twisted mass discretization. To
reduce the amount of zero temperature simulations and the cost of analysis we
have chosen the fixed-scale approach. We show a variety of basic thermodynamic
observables for temperatures ranging from 158 to 633 MeV. Simulations were
performed for three lattice spacings below 0.1 fm each and at a single value of
the pion mass which allows a comparison with previously obtained $N_f=2$
results. We determine the chiral crossover temperature from the bare chiral
susceptibility and show results for the gauge part of the trace anomaly.


title:
Persistence, Change, and the Integration of Objects and Processes in the
  Framework of the General Formal Ontology

abstract:
  In this paper we discuss various problems, associated to temporal phenomena.
These problems include persistence and change, the integration of objects and
processes, and truth-makers for temporal propositions. We propose an approach
which interprets persistence as a phenomenon emanating from the activity of the
mind, and which, additionally, postulates that persistence, finally, rests on
personal identity. The General Formal Ontology (GFO) is a top level ontology
being developed at the University of Leipzig. Top level ontologies can be
roughly divided into 3D-ontologies, and 4D-ontologies. GFO is the only top
level ontology, used in applications, which is a 4D-ontology admitting
additionally 3D objects. Objects and processes are integrated in a natural way.


title:
Origin of a bottom-heavy stellar initial mass function in elliptical
  galaxies

abstract:
  We investigate the origin of a bottom-heavy stellar initial mass function
(IMF) recently observed in elliptical galaxies by using chemical evolution
models with a non-universal IMF. We adopt the Kroupa IMF with the three slopes
(alpha_1, alpha_2, and alpha_3) dependent on metallicities ([Fe/H]) and
densities (rho_g) of star-forming gas clouds and thereby search for the best
IMF model that can reproduce (i) the observed steep IMF slope (alpha_2 ~ 3,
i.e., bottom-heavy) for low stellar masses (m < 1 M_sun) and (ii) the
correlation of alpha_2 with chemical properties of elliptical galaxies in a
self-consistent manner. We find that if the IMF slope alpha_2 depends both on
[Fe/H] and rho_g, then elliptical galaxies with higher [Mg/Fe] can have steeper
alpha_2 (~3) in our models. We also find that the observed positive correlation
of stellar mass-to-light ratios (M/L) with [Mg/Fe] in elliptical galaxies can
be quantitatively reproduced in our models with alpha_2 = beta[Fe/H]}+gamma log
rho_g, where beta ~ 0.5 and gamma ~ 2. We discuss whether the IMF slopes for
low-mass (alpha_2) and high-mass stars (alpha_3) need to vary independently
from each other to explain a number of IMF-related observational results
self-consistently. We also briefly discuss why alpha_2 depends differently on
[Fe/H] in dwarf and giant elliptical galaxies.


title:
Localized excited charge carriers generate ultrafast inhomogeneous
  strain in the multiferroic BiFeO$_3$

abstract:
  We apply ultrafast X-ray diffraction with femtosecond temporal resolution to
monitor the lattice dynamics in a thin film of multiferroic BiFeO$_3$ after
above-bandgap photoexcitation. The sound-velocity limited evolution of the
observed lattice strains indicates a quasi-instantaneous photoinduced stress
which decays on a nanosecond time scale. This stress exhibits an inhomogeneous
spatial profile evidenced by the broadening of the Bragg peak. These new data
require substantial modification of existing models of photogenerated stresses
in BiFeO$_3$: the relevant excited charge carriers must remain localized to be
consistent with the data.


title: The Origin and Pulsations of Extreme Helium Stars

abstract:
  Stars consume hydrogen in their interiors but, generally speaking, their
surfaces continue to contain some 70% hydrogen (by mass) throughout their
lives. Nevertheless, many types of star can be found with hydrogen-deficient
surfaces, in some cases with as little as one hydrogen atom in 10 000. Amongst
these, the luminous B- and A-type extreme helium stars are genuinely rare; only
~15 are known within a very substantial volume of the Galaxy.
  Evidence from surface composition suggests a connection to the cooler R CrB
variables and some of the hotter helium-rich subdwarf O stars. Arguments
currently favour an origin in the merger of two white dwarfs; thus there are
also connections with AM CVn variables and Type Ia supernovae. Pulsations in
many extreme helium stars provide an opportune window into their interiors.
These pulsations have unusual properties, some being "strange" modes, and
others being driven by Z-bump opacities. They have the potential to deliver
distance-independent masses and to provide a unique view of pulsation physics.
  We review the evolutionary origin and pulsations of these stars, and
introduce recent progress and continuing challenges.


title: Photogalvanic current in electron gas over a liquid helium surface

abstract:
  We study the stationary surface photocurrent in 2D electron gas near the
helium surface. Electron gas is assumed to be attracted to the helium surface
due to the image attracting force and an external stationary electric field.
The alternating electric field has both vertical and in-plane components. The
photogalvanic effect originates from the periodic transitions of electrons
between quantum subbands in the vertical direction caused by a normal component
of the alternating electric field accompanied by synchronous in-plane
acceleration/deceleration due to the electric field in-plane component. The
effect needs vertical asymmetry of the system. The problem is considered taking
into account a friction caused by the electron-ripplon interaction. The
photocurrent resonantly depends on the field frequency. The resonance occurs at
field frequencies close to the distance between well subbands. The resonance is
symmetric or antisymmetric depending on the kind (linear or circular) of
polarization.


title: Dark Matter from Decaying Topological Defects

abstract:
  We study dark matter production by decaying topological defects, in
particular cosmic strings. In topological defect or "top-down" (TD) scenarios,
the dark matter injection rate varies as a power law with time with exponent
$p-4$. We find a formula in closed form for the yield for all $p < 3/2$, which
accurately reproduces the solution of the Boltzmann equation. We investigate
two scenarios ($p=1$, $p=7/6$) motivated by cosmic strings which decay into
TeV-scale states with a high branching fraction into dark matter particles. For
dark matter models annihilating either by s-wave or p-wave, we find the regions
of parameter space where the TD model can account for the dark matter relic
density as measured by Planck. We find that topological defects can be the
principal source of dark matter, even when the standard freeze-out calculation
under-predicts the relic density and hence can lead to potentially large "boost
factor" enhancements in the dark matter annihilation rate. We examine dark
matter model-independent limits on this scenario arising from unitarity and
discuss example model-dependent limits coming from indirect dark matter search
experiments. In the four cases studied, the upper bound on $G\mu$ for strings
with an appreciable channel into TeV-scale states is significantly more
stringent than the current Cosmic Microwave Background limits.


title: Ab-initio analysis of plasmon dispersion in sodium under pressure

abstract:
  We present an ab-initio study of the electronic response function of sodium
in its 5 known metallic phases from 0 to 180 GPa at room temperature. The
considered formalism is based on a interpolation scheme within time-dependent
density functional theory that uses maximally localized Wannier functions,
providing an accurate sampling of the reciprocal space. Besides showing an
excellent agreement with inelastic X-ray scattering experiments, our
calculations reveal that the drastic decrease of the optical reflectivity
recently measured in the high pressure phases oP8 and tI19 is associated to a
new low-energy plasmon arising from collective interband excitations.
Additionally, our calculations predict the existence of an anisotropic
interband plasmon in the stability pressure range of fcc Na (65 to 105 GPa).


title:
GIANO-TNG spectroscopy of red supergiants in the young star cluster
  RSGC2

abstract:
  The inner disk of the Galaxy has a number of young star clusters dominated by
red supergiants that are heavily obscured by dust extinction and observable
only at infrared wavelengths. These clusters are important tracers of the
recent star formation and chemical enrichment history in the inner Galaxy.
During the technical commissioning and as a first science verification of the
GIANO spectrograph at the Telescopio Nazionale Galileo, we secured
high-resolution (R~50,000) near-infrared spectra of three red supergiants in
the young Scutum cluster RSGC2. Taking advantage of the full YJHK spectral
coverage of GIANO in a single exposure, we were able to identify several tens
of atomic and molecular lines suitable for chemical abundance determinations.
By means of spectral synthesis and line equivalent width measurements, we
obtained abundances of Fe and other iron-peak elements such as V, Cr, Ni, of
alpha (O, Mg, Si, Ca and Ti) and other light elements (C, N, Na, Al, K, Sc),
and of some s-process elements (Y, Sr). We found iron abundances between half
and one third solar and solar-scaled [X/Fe] abundance patterns of iron-peak,
alpha and most of the light elements, consistent with a thin-disk chemistry. We
found a depletion of [C/Fe] and enhancement of [N/Fe], consistent with CN
burning, and low 12C/13C abundance ratios (between 9 and 11), requiring
extra-mixing processes in the stellar interiors during the post-main sequence
evolution. Finally, we found a slight [Sr/Fe] enhancement and a slight [Y/Fe]
depletion (by a factor of <=2), with respect to solar.


title:
Computer simulations reveal complex distribution of haemodynamic forces
  in a mouse retina model of angiogenesis

abstract:
  There is currently limited understanding of the role played by haemodynamic
forces on the processes governing vascular development. One of many obstacles
to be overcome is being able to measure those forces, at the required
resolution level, on vessels only a few micrometres thick. In the current
paper, we present an in silico method for the computation of the haemodynamic
forces experienced by murine retinal vasculature (a widely used vascular
development animal model) beyond what is measurable experimentally. Our results
show that it is possible to reconstruct high-resolution three-dimensional
geometrical models directly from samples of retinal vasculature and that the
lattice-Boltzmann algorithm can be used to obtain accurate estimates of the
haemodynamics in these domains. We generate flow models from samples obtained
at postnatal days (P) 5 and 6. Our simulations show important differences
between the flow patterns recovered in both cases, including observations of
regression occurring in areas where wall shear stress gradients exist. We
propose two possible mechanisms to account for the observed increase in
velocity and wall shear stress between P5 and P6: i) the measured reduction in
typical vessel diameter between both time points, ii) the reduction in network
density triggered by the pruning process. The methodology developed herein is
applicable to other biomedical domains where microvasculature can be imaged but
experimental flow measurements are unavailable or difficult to obtain.


title: How many $n$-vertex triangulations does the $3$-sphere have?

abstract:
  It is known that the $3$-sphere has at most $2^{O(n^2 \log n)}$
combinatorially distinct triangulations with $n$ vertices. Here we construct at
least $2^{\Omega(n^2)}$ such triangulations.


title: Quasi-Linear Compressed Sensing

abstract:
  Inspired by significant real-life applications, in particular, sparse phase
retrieval and sparse pulsation frequency detection in Asteroseismology, we
investigate a general framework for compressed sensing, where the measurements
are quasi-linear. We formulate natural generalizations of the well-known
Restricted Isometry Property (RIP) towards nonlinear measurements, which allow
us to prove both unique identifiability of sparse signals as well as the
convergence of recovery algorithms to compute them efficiently. We show that
for certain randomized quasi-linear measurements, including Lipschitz
perturbations of classical RIP matrices and phase retrieval from random
projections, the proposed restricted isometry properties hold with high
probability. We analyze a generalized Orthogonal Least Squares (OLS) under the
assumption that magnitudes of signal entries to be recovered decay fast. Greed
is good again, as we show that this algorithm performs efficiently in phase
retrieval and asteroseismology. For situations where the decay assumption on
the signal does not necessarily hold, we propose two alternative algorithms,
which are natural generalizations of the well-known iterative hard and
soft-thresholding. While these algorithms are rarely successful for the
mentioned applications, we show their strong recovery guarantees for
quasi-linear measurements which are Lipschitz perturbations of RIP matrices.


title: Volume Law for the Entanglement Entropy in Non-local QFTs

abstract:
  In this paper, we present a simple class of non-local field theories whose
ground state entanglement entropy follows a volume law as long as the size of
subsystem is smaller than a certain scale. We will confirm this volume law both
from numerical calculations and from analytical estimation. This behavior fits
nicely with holographic results for spacetimes whose curvatures are much
smaller than AdS spaces such as those in the flat spacetime.