title:
Local immobilization of particles in mass transfer described by the
  equation of the Jeffreys type

abstract:
  We consider the equation of the Jeffreys type as the basic one in three
different models of mass transfer, namely, the Jeffreys type and two-phase
models, and the $D_1$ approximation to the linear Boltzmann equation. We study
two classic 1 + 1D problems in the framework of each model. The first problem
is the transfer of a substance initially confined in a point. The second
problem is the transfer of a substance from a stationary point source. We
calculate the mean-square displacement (MSD) for the solutions of the first
problem. The temporal behaviour of the MSD in the framework of the first and
third models is found to be the same as that in the Brownian motion described
by the standard Langevin equation. Besides, we find a remarkable phenomenon
when a portion of the substance does not move.

categories: cond-mat.stat-mech math-ph math.MP physics.bio-ph q-bio.QM


title: Characterize graphs with rainbow connection number $m-2$ and $m-3$

abstract:
  A path in an edge-colored graph, where adjacent edges may be colored the
same, is a rainbow path if no two edges of it are colored the same. A
nontrivial connected graph $G$ is rainbow connected if there is a rainbow path
connecting any two vertices, and the rainbow connection number of $G$, denoted
by $rc(G)$, is the minimum number of colors that are needed in order to make
$G$ rainbow connected. Chartrand et al. obtained that $G$ is a tree if and only
if $rc(G)=m$, and it is easy to see that $G$ is not a tree if and only if
$rc(G)\leq m-2$, where $m$ is the number of edge of $G$. So there is an
interesting problem: Characterize the graphs $G$ with $rc(G)=m-2$. In this
paper, we settle down this problem. Furthermore, we also characterize the
graphs $G$ with $rc(G)=m-3$.


title: Graphs with $4$-rainbow index $3$ and $n-1$

abstract:
  Let $G$ be a nontrivial connected graph with an edge-coloring
$c:E(G)\rightarrow \{1,2,\ldots,q\},$ $q\in \mathbb{N}$, where adjacent edges
may be colored the same. A tree $T$ in $G$ is called a $rainbow~tree$ if no two
edges of $T$ receive the same color. For a vertex set $S\subseteq V(G)$, a tree
that connects $S$ in $G$ is called an {\it $S$-tree}. The minimum number of
colors that are needed in an edge-coloring of $G$ such that there is a rainbow
$S$-tree for every $k$-set $S$ of $V(G)$ is called the {\it $k$-rainbow index}
of $G$, denoted by $rx_k(G)$. Notice that an lower bound and an upper bound of
the $k$-rainbow index of a graph with order $n$ is $k-1$ and $n-1$,
respectively. Chartrand et al. got that the $k$-rainbow index of a tree with
order $n$ is $n-1$ and the $k$-rainbow index of a unicyclic graph with order
$n$ is $n-1$ or $n-2$. Li and Sun raised the open problem of characterizing the
graphs of order $n$ with $rx_k(G)=n-1$ for $k\geq 3$. In early papers we
characterized the graphs of order $n$ with 3-rainbow index 2 and $n-1$. In this
paper, we focus on $k=4$, and characterize the graphs of order $n$ with
4-rainbow index 3 and $n-1$, respectively.


title:
Molecular Motor-Powered Shuttles along Multi-walled Carbon Nanotube
  Tracks

abstract:
  As a complementary tool to nanofluidics, biomolecular based transport is
envisioned for nanotechnological devices. We report a new method for guiding
microtubule shuttles on multi-walled carbon nanotube tracks, aligned by
dielectrophoresis on a functionalized surface. In the absence of electric field
and in fluid flow, alignment is maintained. The directed translocation of
kinesin propelled microtubules has been investigated using fluorescence
microscopy. To our knowledge, this is the first demonstration of microtubules
gliding along carbon nanotubes.


title: Theory of superconductivity in SrPtAs

abstract:
  We constructed tight-binding models for the new superconductor SrPtAs
according to first principle calculations, and by functional renormalization
group we investigated the effect of electron correlations and spin-orbital
coupling (SOC) in Cooper pairing. We found that out of the five $d$-orbitals,
the $(xz,yz)$-orbitals are the active ones responsible for superconductivity,
and ferromagnetic fluctuations enhanced by the proximity to the van Hove
singularity triggers $f$-wave triplet pairing. The superconducting transition
temperature increases as the Fermi level is closer to the van Hove singularity
until ferromagnetism sets in. The $d$-vector of the triplet pairing component
is pinned by SOC along the out-of-plane direction. Experimental perspectives
are discussed.


title: Forests and Trees among Gallai Graphs

abstract:
  The Gallai graph $\Gamma(G)$ of a graph $G$ has the edges of $G$ as its
vertices and two distinct vertices $e$ and $f$ of $\Gamma(G)$ are adjacent in
$\Gamma(G)$ if the edges $e$ and $f$ of $G$ are adjacent in $G$ but do not span
a triangle in $G$. Clearly, $\Gamma(G)$ is a subgraph of the line graph of $G$.
While line graphs can be recognized efficiently the complexity of recognizing
Gallai graphs is unknown. In the present paper we characterize those graphs
whose Gallai graphs are forests or trees, respectively.


title: A finite-temperature Monte Carlo algorithm for network forming materials

abstract:
  Computer simulations of structure formation in network forming materials
(such as amorphous semiconductors, glasses, or fluids containing hydrogen
bonds) are challenging. The problem is that large structural changes in the
network topology are rare events, making it very difficult to equilibrate these
systems. To overcome this problem, Wooten, Winer and Weaire [PRL 54, 1392
(1985)] proposed a Monte Carlo bond-switch move, constructed to alter the
network topology at every step. The resulting algorithm is well suited to study
networks at zero temperature. However, since thermal fluctuations are ignored,
it cannot be used to probe the phase behavior at finite temperature. In this
paper, a modification of the original bond-switch move is proposed, in which
detailed balance and ergodicity are both obeyed, thereby facilitating a correct
sampling of the Boltzmann distribution for these systems at any finite
temperature. The merits of the modified algorithm are demonstrated in a
detailed investigation of the melting transition in a two-dimensional 3-fold
coordinated network.


title: Effect of recrystallization on diffusion in ultrafine grained Ni

abstract:
  We studied the effect of recrystallization and grain growth on grain boundary
self-diffusion in ultrafine grained Ni prepared by high pressure torsion. Two
Ni materials of low (99.6 wt. %) and high (99.99 wt. %) purity levels were
compared and the kinetic properties of stationary and mobile grain boundaries
were examined in detail. Unusual concentration profiles with characteristic
'kinks' were measured for Ni self-diffusion in 99.99 wt. % pure Ni, which is
undergoing recrystallization and grain growth during diffusion annealing
treatment. This behavior is found to be related to specific kinetic properties
of grain boundaries which encompass the recrystallized areas and consume
numerous defects of the ultrafine grained matrix during their motion. We
proposed a model of self-diffusion in recrystallizing material which takes into
account a hierarchy of stationary and moving fast diffusion paths, and
satisfactory explains the observed diffusion behavior.


title: Longest Paths in Circular Arc Graphs

abstract:
  As observed by Rautenbach and Sereni (arXiv:1302.5503) there is a gap in the
proof of the theorem of Balister et al. (Longest paths in circular arc graphs,
Combin. Probab. Comput., 13, No. 3, 311-317 (2004)), which states that the
intersection of all longest paths in a connected circular arc graph is
nonempty. In this paper we close this gap.


title: A Koszul filtration for the second squarefree Veronese subring

abstract:
  The second squarefree Veronese subring in $n$ variables is the edge ring of
the complete graph with $n$ vertices. It is proved that every second squarefree
Veronese subring possesses a Koszul filtration.


title:
How have the Eastern European countries of the former Warsaw Pact
  developed since 1990? A bibliometric study

abstract:
  Did the demise of the Soviet Union in 1991 influence the scientific
performance of the researchers in Eastern European countries? Did this
historical event affect international collaboration by researchers from the
Eastern European countries with those of Western countries? Did it also change
international collaboration among researchers from the Eastern European
countries? Trying to answer these questions, this study aims to shed light on
international collaboration by researchers from the Eastern European countries
(Russia, Ukraine, Belarus, Moldova, Bulgaria, the Czech Republic, Hungary,
Poland, Romania and Slovakia). The number of publications and normalized
citation impact values are compared for these countries based on InCites
(Thomson Reuters), from 1981 up to 2011. The international collaboration by
researchers affiliated to institutions in Eastern European countries at the
time points of 1990, 2000 and 2011 was studied with the help of Pajek and
VOSviewer software, based on data from the Science Citation Index (Thomson
Reuters). Our results show that the breakdown of the communist regime did not
lead, on average, to a huge improvement in the publication performance of the
Eastern European countries and that the increase in international co-authorship
relations by the researchers affiliated to institutions in these countries was
smaller than expected. Most of the Eastern European countries are still subject
to changes and are still awaiting their boost in scientific development.


title:
Data Transformations and Goodness-of-Fit Tests for Type-II Right
  Censored Samples

abstract:
  We suggest several goodness-of-fit methods which are appropriate with Type-II
right censored data. Our strategy is to transform the original observations
from a censored sample into an approximately i.i.d. sample of normal variates
and then perform a standard goodness-of-fit test for normality on the
transformed observations. A simulation study with several well known parametric
distributions under testing reveals the sampling properties of the methods. We
also provide theoretical analysis of the proposed method.


title: Molecular Clouds in the North American and Pelican Nebulae: Structures

abstract:
  We present observations of 4.25 square degree area toward the North American
and Pelican Nebulae in the $J = 1-0$ transitions of $^{12}$CO, $^{13}$CO, and
C$^{18}$O. Three molecules show different emission area with their own distinct
structures. These different density tracers reveal several dense clouds with
surface density over 500 $M_\odot$ pc$^{-2}$ and a mean H$_2$ column density of
5.8, 3.4, and 11.9$\times10^{21}$ cm$^{-2}$ for $^{12}$CO, $^{13}$CO, and
C$^{18}$O, respectively. We obtain a total mass of $5.4\times10^4 M_\odot$
($^{12}$CO), $2.0\times10^4 M_\odot$ ($^{13}$CO), and $6.1\times10^3 M_\odot$
(C$^{18}$O) in the complex. The distribution of excitation temperature shows
two phase of gas: cold gas ($\sim$10 K) spreads across the whole cloud; warm
gas ($>$20 K) outlines the edge of cloud heated by the W80 H II region. The
kinetic structure of the cloud indicates an expanding shell surrounding the
ionized gas produced by the H II region. There are six discernible regions in
the cloud including the Gulf of Mexico, Caribbean Islands and Sea, Pelican's
Beak, Hat, and Neck. The areas of $^{13}$CO emission range within 2-10 pc$^2$
with mass of (1-5)$\times10^3 M_\odot$ and line width of a few km s$^{-1}$. The
different line properties and signs of star forming activity indicate they are
in different evolutionary stages. Four filamentary structures with complicated
velocity features are detected along the dark lane in LDN 935. Furthermore, a
total of 611 molecular clumps within the $^{13}$CO tracing cloud are identified
using the ClumpFind algorithm. The properties of the clumps suggest most of the
clumps are gravitationally bound and at an early stage of evolution with cold
and dense molecular gas.


title: Stringent and efficient assessment of Boson-Sampling devices

abstract:
  Boson-Sampling holds the potential to experimentally falsify the Extended
Church Turing thesis. The computational hardness of Boson-Sampling, however,
complicates the certification that an experimental device yields correct
results in the regime in which it outmatches classical computers. To certify a
boson-sampler, one needs to verify quantum predictions and rule out models that
yield these predictions without true many-boson interference. We show that a
semiclassical model for many-boson propagation reproduces coarse-grained
observables that were proposed as witnesses of Boson-Sampling. A test based on
Fourier matrices is demonstrated to falsify physically plausible alternatives
to coherent many-boson propagation.


title: Ultimate survival in anomalous psi(2S) decays

abstract:
  The hierarchy among the radiative $\gamma$($\pi^0$, $\eta$, $\eta^{\prime}$)
decay channels for the $\psi^{\prime}$ looks quite different from the $J/\psi$
one. The fate of charm, namely an ultimate survival of on-shell $c \bar{c}$
intermediate states, might give us the clue for this new puzzle in exclusive
charmonium decays. A similar self-preservation has already been invoked in the
past to solve the so-called $\rho \pi$ puzzle.


title:
The QCD analysis of xF_3 structure function based on the analytic
  approach

abstract:
  We apply analytic perturbation theory to the QCD analysis of the xF_3
structure function data of the CCFR collaboration. We use different approaches
for the leading order Q^2 evolution of the xF_3 structure function and compare
the extracted values of the parameter Lambda_QCD and the shape of the higher
twistcontribution. Our consideration is based on the Jacobi polynomial
expansion method of the unpolarized structure function. The analysis shows that
the analytic approach provides reasonable results in the leading order QCD
analysis.


title:
f(R)-Gravity: "Einstein Frame" Lagrangian Formulation, Non-Standard
  Black Holes and QCD-like Confinement/Deconfinement

abstract:
  We consider f(R) = R + R^2 gravity interacting with a dilaton and a special
non-standard form of nonlinear electrodynamics containing a square-root of
ordinary Maxwell Lagrangian. In flat spacetime the latter arises due to a
spontaneous breakdown of scale symmetry and produces an effective
charge-confining potential. In the R + R^2 gravity case, upon deriving the
explicit form of the equivalent local "Einstein frame" Lagrangian action, we
find several physically relevant features due to the combined effect of the
gauge field and gravity nonlinearities such as: appearance of dynamical
effective gauge couplings and confinement-deconfinement transition effect as
functions of the dilaton vacuum expectation value; new mechanism for dynamical
generation of cosmological constant; deriving non-standard black hole solutions
carrying additional constant vacuum radial electric field and with
non-asymptotically flat "hedge-hog"-type spacetime asymptotics.


title:
Ultrasonic Study of the Hidden Order and Heavy-Fermion State in
  URu$_2$Si$_2$ with Hydrostatic Pressure, Rh-doping, and High-Magnetic Fields

abstract:
  This paper reports recent progress of ultrasonic measurements on
URu$_2$Si$_2$, including ultrasonic measurements under hydrostatic pressure, in
pulsed-magnetic fields, and the effect of Rh-substitution. The observed changes
of the elastic responses shed light on the orthorhombic-lattice instability
with $\Gamma_3$-symmetry existing within the hidden order and the hybridized
5$f$-electron states of URu$_2$Si$_2$.


title: From stellar nebula to planets: the refractory components

abstract:
  We computed the abundance of refractory elements in planetary bodies formed
in stellar systems with solar chemical composition by combining models for
chemical composition and planet formation. We also consider the formation of
refractory organic compounds, which have been ignored in previous studies on
this topic. We used the commercial software package HSC Chemistry in order to
compute the condensation sequence and chemical composition of refractory
minerals incorporated into planets. The problem of refractory organic material
is approached with two distinct model calculations: the first considers that
the fraction of atoms used in the formation of organic compounds is removed
from the system (i.e. organic compounds are formed in the gas phase and are
nonreactive); and the second assumes that organic compounds are formed by the
reaction between different compounds that had previously condensed from the gas
phase. Results show that refractory material represents more than 50 wt % of
the mass of solids accreted by the simulated planets, with up to 30 wt % of the
total mass composed of refractory organic compounds. Carbide and silicate
abundances are consistent with C/O and Mg/Si elemental ratios of 0.5 and 1.02
for the Sun. Less than 1 wt % of carbides; pyroxene and olivine in similar
quantities are formed. The model predicts planets that are similar in
composition to those of the Solar system. It also shows that, starting from a
common initial nebula composition, a wide variety of chemically different
planets can form, which means that the differences in planetary compositions
are due to differences in the planetary formation process. We show that a model
in which refractory organic material is absent from the system is more
compatible with observations. The use of a planet formation model is essential
to form a wide diversity of planets in a consistent way.


title:
Quantum repeater with Rydberg blocked atomic ensembles in fiber-coupled
  cavities

abstract:
  We propose and analyze a quantum repeater architecture in which Rydberg
blocked atomic ensembles inside optical cavities are linked by optical fibers.
Entanglement generation, swapping and purification are achieved through
collective laser manipulations of the ensembles and photon transmission.
Successful transmission and storage of entanglement are heralded by ionization
events rather than by photon detection signal used in previous proposals. We
demonstrate how the high charge detection efficiency allows for a shortened
average entanglement generation time, and we analyze an implementation of our
scheme with ensembles of Cs atoms.


title: Generalized Heavy-to-Light Form Factors in Light-Cone Sum Rules

abstract:
  We study the form factors for a heavy meson into the S-wave $K\pi/\pi\pi$
system with an invariant mass below 1~GeV. The mesonic final state interactions
are described in terms of the scalar form factors, which are obtained from
unitarized chiral perturbation theory. Employing generalized light-cone
distribution amplitudes, we compute the heavy-to-light transition using
light-cone sum rules. Our approach simultaneously respects constraints from
analyticity and unitarity, and also takes advantage of the power expansion in
the $1/m_b$ and the strong coupling constant.


title: The Lagrangian Formulation of Strong-Field QED in a Plasma

abstract:
  The Lagrangian formulation of the scalar and spinor quantum electrodynamics
(QED) in the presence of strong laser fields in a plasma medium is considered.
We include the plasma influence in the free Lagrangian analogously to the
"Furry picture" and obtain coupled equations of motion for the plasma particles
and for the laser propagation. We demonstrate that the strong-field wave (i.e.
the laser) satisfies a massive dispersion relation and obtain self-consistently
the effective mass of the laser photons. The Lagrangian formulation derived in
this paper is the basis for the cross sections calculation of quantum processes
taking place in the presence of a plasma.


title: Quasiperiodic graphs at the onset of chaos

abstract:
  We examine the connectivity fluctuations across networks obtained when the
horizontal visibility (HV) algorithm is used on trajectories generated by
nonlinear circle maps at the quasiperiodic transition to chaos. The resultant
HV graph is highly anomalous as the degrees fluctuate at all scales with
amplitude that increases with the size of the network. We determine families of
Pesin-like identities between entropy growth rates and generalized
graph-theoretical Lyapunov exponents. An irrational winding number with pure
periodic continued fraction characterizes each family. We illustrate our
results for the so-called golden, silver and bronze numbers.


title: Quasi-stochastic matrices and Markov renewal theory

abstract:
  Given a matrix of distribution functions and a quasi-stochastic matrix, i.e.
an irreducible nonnegative matrix with maximal eigenvalue one and associated
unique positive left and right eigenvectors, the article studies the properties
of an associated matrix renewal measure and a related integral equation. Unlike
earlier work this is done by a purely probabilistic approach based on a simple
harmonic transform. Main results include Markov renewal-type theorems and a
Stone-type decomposition under an absolute continuity condition. Three
applications are given at the end of the paper.


title:
Generalization of the Blumenthal-Getoor index to the class of
  homogeneous diffusions with jumps and some applications

abstract:
  We introduce the probabilistic symbol for the class of homogeneous diffusions
with jumps (in the sense of Jacod/Shiryaev). This concept generalizes the
well-known characteristic exponent of a L\'{e}vy process. Using the symbol, we
introduce eight indices which generalize the Blumenthal-Getoor index $\beta$
and the Pruitt index $\delta$. These indices are used afterwards to obtain
growth and H\"{o}lder conditions of the process. In the future, the technical
main results will be used to derive further fine properties. Since virtually
all examples of homogeneous diffusions in the literature are Markovian, we
construct a process which does not have this property.


title:
A Low-Complexity Detector for Memoryless Polarization-Multiplexed
  Fiber-Optical Channels

abstract:
  A low-complexity detector is introduced for polarization-multiplexed M-ary
phase shift keying modulation in a fiber-optical channel impaired by nonlinear
phase noise, generalizing a previous result by Lau and Kahn for
single-polarization signals. The proposed detector uses phase compensation
based on both received signal amplitudes in conjunction with simple
straight-line rather than four-dimensional maximum-likelihood decision
boundaries.


title: Detection of Symmetry Enriched Topological Phases

abstract:
  Topologically ordered systems in the presence of symmetries can exhibit new
structures which are referred to as symmetry enriched topological (SET) phases.
We introduce simple methods to detect the SET order directly from a complete
set of topologically degenerate ground state wave functions. In particular, we
first show how to directly determine the characteristic symmetry
fractionalization of the quasiparticles from the reduced density matrix of the
minimally entangled states. Second, we show how a simple generalization of a
non-local order parameter can be measured to detect SETs. The usefulness of the
proposed approached is demonstrated by examining two concrete model states
which exhibit SET: (i) a spin-1 model on the honeycomb lattice and (ii) the
resonating valence bond state on a kagome lattice. We conclude that the spin-1
model and the RVB state are in the same SET phases.


title: On the equivalence of modes of convergence for log-concave measures

abstract:
  An important theme in recent work in asymptotic geometric analysis is that
many classical implications between different types of geometric or functional
inequalities can be reversed in the presence of convexity assumptions. In this
note, we explore the extent to which different notions of distance between
probability measures are comparable for log-concave distributions. Our results
imply that weak convergence of isotropic log-concave distributions is
equivalent to convergence in total variation, and is further equivalent to
convergence in relative entropy when the limit measure is Gaussian.


title:
On the role of Schwinger's SU(2) generators for Simple Harmonic
  Oscillator in 2D Moyal plane

abstract:
  The Hilbert-Schmidt operator formulation of non-commutative quantum mechanics
in 2D Moyal plane is shown to allow one to construct Schwinger's SU(2)
generators. Using this the SU(2) symmetry aspect of both commutative and
non-commutative harmonic oscillator are studied and compared. Particularly, in
the non-commutative case we demonstrate the existence of a critical point in
the parameter space of mass and angular frequency where there is a manifest
SU(2) symmetry for a unphysical harmonic oscillator Hamiltonian built out of
commuting (unphysical yet covariantly transforming under SU(2)) position like
observable. The existence of this critical point is shown to be a novel aspect
in non-commutative harmonic oscillator, which is exploited to obtain the
spectrum and the observable mass and angular frequency parameters of the
physical oscillator-which is generically different from the bare parameters
occurring in the Hamiltonian. Finally, we show that a Zeeman term in the
Hamiltonian of non-commutative physical harmonic oscillator, is solely
responsible for both SU(2) and time reversal symmetry breaking.


title: Measurement of hard double-parton interactions with the ATLAS detector

abstract:
  The production of W boson in association with two jets in proton-proton
collisions at the LHC with a centre-of-mass energy of $\sqrt{s}$ = 7 TeV has
been investigated using data collected with the ATLAS detector. The fraction of
events arising from double-parton scattering has been measured through the
transverse momentum balance between the two jets. The measurement provides new
information on the scaling of the rate of double-parton scattering processes
and constraints on proton transverse profile modeling.


title: Thermalization after/during Reheating

abstract:
  If reheating of the Universe takes place via Planck-suppressed decay, it
seems that the thermalization of produced particles might be delayed, since
they have large energy/small number densities and number violating large angle
scatterings which decrease the momentum of particles by large amount are
inefficient correspondingly. In this paper, we study the thermalization of such
"under occupied" decay products in detail, following recent developments in
understanding the thermalization of non-abelian plasma. Contrary to the above
naive expectation, it is shown that in most cases thermalization after/during
reheating occurs instantaneously by properly taking account of scatterings with
small angles and of particles with small momenta. In particular, the condition
for instantaneous thermalization before the completion of reheating is found to
be $\alpha^{8/5} \gg (m_\phi / M_{\rm pl}) (M_{\rm pl}^2 \Gamma_\phi /
m_\phi^3)^{1/5}$, which is much milder than that obtained in previous works
with small angle scatterings taken into account.


title: Ergodicity of principal algebraic group actions

abstract:
  An \textit{algebraic} action of a discrete group $\Gamma $ is a homomorphism
from $\Gamma $ to the group of continuous automorphisms of a compact abelian
group $X$. By duality, such an action of $\Gamma $ is determined by a module
$M=\widehat{X}$ over the integer group ring $\mathbb{Z}\Gamma $ of $\Gamma $.
The simplest examples of such modules are of the form $M=\mathbb{Z}\Gamma
/\mathbb{Z}\Gamma f$ with $f\in \mathbb{Z}\Gamma $; the corresponding algebraic
action is the \textit{principal algebraic $\Gamma $-action} $\alpha _f$ defined
by $f$.
  In this note we prove the following extensions of results by Hayes
\cite{Hayes} on ergodicity of principal algebraic actions: If $\Gamma $ is a
countably infinite discrete group which is not virtually cyclic, and if
$f\in\mathbb{Z}\Gamma $ satisfies that right multiplication by $f$ on $\ell
^2(\Gamma ,\mathbb{R})$ is injective, then the principal $\Gamma $-action
$\alpha _f$ is ergodic (Theorem \ref{t:ergodic2}). If $\Gamma $ contains a
finitely generated subgroup with a single end (e.g. a finitely generated
amenable subgroup which is not virtually cyclic), or an infinite nonamenable
subgroup with vanishing first $\ell ^2$-Betti number (e.g., an infinite
property $T$ subgroup), the injectivity condition on $f$ can be replaced by the
weaker hypothesis that $f$ is not a right zero-divisor in $\mathbb{Z}\Gamma $
(Theorem \ref{t:ergodic1}). Finally, if $\Gamma $ is torsion-free, not
virtually cyclic, and satisfies Linnell's \textit{analytic zero-divisor
conjecture}, then $\alpha _f$ is ergodic for every $f\in \mathbb{Z}\Gamma $
(Remark \ref{r:analytic zero divisor}).


title: Persistent memory in athermal systems in deformable energy landscapes

abstract:
  We show that memory can be encoded in a model amorphous solid subjected to
athermal oscillatory shear deformations, and in an analogous spin model with
disordered interactions, sharing the feature of a deformable energy landscape.
When these systems are subjected to oscillatory shear deformation, they retain
memory of the deformation amplitude imposed in the training phase, when the
amplitude is below a "localization" threshold. Remarkably, multiple,
persistent, memories can be stored using such an athermal, noise-free,
protocol. The possibility of such memory is shown to be linked to the presence
of plastic deformations and associated limit cycles traversed by the system,
which exhibit avalanche statistics also seen in related contexts.


title:
Modelling of the optical properties of silver with use of six fitting
  parameters

abstract:
  We propose a realistic model of the optical properties of silver, in which
inter-band transition with a threshold energy of ~ 4 eV is described
phenomenologically by an ensemble of oscillators with same damping constant and
a certain distribution of resonant frequencies in the interband transition
threshold to infinity. The contribution of the conduction electrons in the
dielectric function is determined by the Drude formula. The proposed model
actually contains the features of both the Drude-Lorentz model (Raki\'c et al.
1998) and Tauc-Lorentz model (Jian-Hong Qiu et al. 2005). However, unlike these
works proposed model contains only six fitting parameters, with the square root
of the mean square deviation of the absorption coefficient and refractive index
of silver from the experimental values in the range of 0.6 nm - 6.0 nm being of
the order of 0.05.


title: Thermoacoustic instability - a dynamical system and time domain analysis

abstract:
  This study focuses on the Rijke tube problem, which includes features
relevant to the modeling of thermoacoustic coupling in reactive flows: a
compact acoustic source, an empirical model for the heat source, and
nonlinearities. This thermo-acoustic system features a complex dynamical
behavior. In order to synthesize accurate time-series, we tackle this problem
from a numerical point-of-view, and start by proposing a dedicated solver
designed for dealing with the underlying stiffness, in particular, the retarded
time and the discontinuity at the location of the heat source. Stability
analysis is performed on the limit of low-amplitude disturbances by means of
the projection method proposed by Jarlebring (2008), which alleviates the
linearization with respect to the retarded time. The results are then compared
to the analytical solution of the undamped system, and to Galerkin projection
methods commonly used in this setting. This analysis provides insight into the
consequences of the various assumptions and simplifications that justify the
use of Galerkin expansions based on the eigenmodes of the unheated resonator.
We illustrate that due to the presence of a discontinuity in the spatial
domain, the eigenmodes in the heated case, predicted by using Galerkin
expansion, show spurious oscillations resulting from the Gibbs phenomenon. By
comparing the modes of the linear to that of the nonlinear regime, we are able
to illustrate the mean-flow modulation and frequency switching. Finally,
time-series in the fully nonlinear regime, where a limit cycle is established,
are analyzed and dominant modes are extracted. The analysis of the saturated
limit cycles shows the presence of higher frequency modes, which are linearly
stable but become significant through nonlinear growth of the signal. This
bimodal effect is not captured when the coupling between different frequencies
is not accounted for.


title:
Viscosity-Induced Crossing of the Phantom Divide in the Dark Cosmic
  Fluid

abstract:
  Choosing various natural forms for the equation-of-state parameter w and the
bulk viscosity \zeta, we discuss how it is possible for a dark energy fluid to
slide from the quintessence region across the divide w=-1 into the phantom
region, and thus into a Big Rip future singularity. Different analytic forms
for \zeta, as powers of the scalar expansion, are suggested and compared with
experiments.


title:
Groupe de Brauer non ramifi\'e alg\'ebrique des espaces homog\`enes (The
  unramified algebraic Brauer group of homogeneous spaces)

abstract:
  Using a reduction of the Galois cohomology of a linear algebraic group $G$ to
that of a certain finite subquotient, we give different formulas allowing the
calculation of the unramified algebraic Brauer group of a homogeneous space
$V=G\backslash G'$ with $G'$ semisimple and simply connected, both over a
finite field and over an arbitrary field of characteristic $0$.


title:
Modelling of three dimensional equilibrium and stability of MAST plasmas
  with magnetic perturbations using VMEC and COBRA

abstract:
  It is known that magnetic perturbations can mitigate edge localized modes
(ELMs) in experiments, for example MAST (Kirk et al 2013 Nucl. Fusion 53
043007). One hypothesis is that the magnetic perturbations cause a three
dimensional corrugation of the plasma and this corrugated plasma has different
stability properties to peeling-ballooning modes compared to an axisymmetric
plasma. It has been shown in an up-down symmetric plasma that magnetic
perturbations in tokamaks will break the usual axisymmetry of the plasma
causing three dimensional displacements (Chapman et al 2012 Plasma Phys.
Control. Fusion 54 105013). We produce a free boundary three-dimensional
equilibrium of a lower single null MAST relevant plasma using VMEC (S P
Hirshman and J C Whitson 1983 Phys. Fluids 26 3553). The current and pressure
profiles used for the modelling are similar to those deduced from axisymmetric
analysis of experimental data with ELMs. We focus on the effect of applying
$n=3$ and $n=6$ magnetic perturbations using the RMP coils. A midplane
displacement of over $\pm 1$ cm is seen when the full current is applied. The
current in the coils is scaned and a linear relationship between coil current
and midplane displacement is found. The effect of this non-axisymmetric
equilibrium on infinite $n$ ballooning stability is investigated using COBRA (R
Sanchez et al 2000 J. Comput. Phys. 161 576-588).


title: Quantum spectroscopy of plasmonic nanostructures

abstract:
  We use frequency entangled photons, generated via spontaneous parametric down
conversion, to measure the broadband spectral response of an array of gold
nanoparticles exhibiting Fano-type plasmon resonance. Refractive index sensing
of a liquid is performed by measuring the shift of the array resonance. This
method is robust in excessively noisy conditions compared with conventional
broadband transmission spectroscopy. Detection of a refractive index change is
demonstrated with a noise level 70 times higher than the signal, which is shown
to be inaccessible with the conventional transmission spectroscopy. Use of low
photon fluxes makes this method suitable for measurements of photosensitive
bio-samples and chemical substances.


title: Confotronic Dynamics of Tubular Lattices

abstract:
  Tubular lattices are ubiquitous in nature and technology. Microtubules and
nanotubes of all kinds act as important pillars of biological cells and the
man-made nano-world. We show that when prestress is introduced in such
structures, localized conformational quasiparticles emerge and govern the
collective shape dynamics of the lattice.
  When coupled via cooperative interactions these quasiparticles form
larger-scale quasipolymer superstructures exhibiting collective dynamic modes
and giving rise to a hallmark behavior radically different from semiflexible
beams.


title: Lehmer's totient problem over $\mathbb{F}_q[x]$

abstract:
  In this paper, we consider the function field analogue of the Lehmer's
totient problem. Let $p(x)\in\mathbb{F}_q[x]$ and $\varphi(q,p(x))$ be the
Euler's totient function of $p(x)$ over $\mathbb{F}_q[x],$ where $\mathbb{F}_q$
is a finite field with $q$ elements. We prove that $\varphi(q,p(x))|(q^{{\rm
deg}(p(x))}-1)$ if and only if (i) $p(x)$ is irreducible; or (ii) $q=3, \;
p(x)$ is the product of any $2$ non-associate irreducibes of degree $1;$ or
(iii) $q=2,\; p(x)$ is the product of all irreducibles of degree $1,$ all
irreducibles of degree $1$ and $2,$ and the product of any $3$ irreducibles one
each of degree $1, 2$ and $3$.


title: Maximal height of divisors of $x^{pq^{b}}-1$

abstract:
  The height of a polynomial $f(x)$ is the largest coefficient of $f(x)$ in
absolute value. Let B(n) be the largest height of a polynomial in
$\mathbb{Z}[x]$ dividing $x^n-1$. In this paper we investigate the maximal
height of divisors of $x^{pq^b}-1$ and prove that some conjectures on the
maximal height of divisors of $x^{pq^b}-1$ are true.


title: Status of the JET LIDAR Thomson Scattering diagnostic

abstract:
  The LIDAR Thomson scattering concept was proposed in 1983 and then
implemented for the first time on the JET tokamak in 1987. A number of
modifications were performed and published in 1995, but since then no major
changes were made for almost 15 years. In 2010 a refurbishment of the
diagnostic was started, with as main goals to improve its performance and to
test the potential of new detectors which are considered as candidates for
ITER. During the subsequent years a wide range of activities was performed
aimed at increasing the diagnostic's light throughput, improvement of signal to
noise ratio and amendment of the calibration procedures. Previously used MA-2
detectors were replaced by fast GaAsP detectors with much higher average QE.
After all the changes were implemented, a significant improvement of the
measured data was achieved. Statistical errors of measured temperature and
density were reduced by a factor of 2 or more, depending on plasma conditions,
and comfortably surpassed the values requested for ITER Core Thomson Scattering
(10% for Te and 5% for ne). Excellent agreement with other diagnostics
(conventional High Resolution Thomson Scattering, ECE, Reflectometer) was
achieved over a wide range of plasma conditions. It was demonstrated that
together with long term reliability and modest access port requirements, LIDAR
can provide measurements of a quality similar to a conventional imaging Thomson
Scattering instrument.


title: Construction of Spacetime Field and Quantization of General Relativity

abstract:
  Theories based on General Relativity or Quantum Mechanics have taken a
leading position in macroscopic and microscopic Physics, but fail when used in
the other extremity. Thus, we try to establish a new structure of united theory
based on General Relativity by forming certain spacetime property and a new
model of particle. This theory transforms the Riemann curvature tensor into
spacetime density scalar so that gravitational field can be added to the
Quantum Mechanics, and supposes the electromagnetic field in General Relativity
to be a kind of spacetime fluid. Also the theory carries on Einstein-Cartan
Theory about spacetime torsion to form the energy exchange in order that
Hubble's law and dark mass can be simply explained. On the basis of the
definition of signal, measurement and observation, the theory is able to
construct a modified Quantum Equation in curved spacetime compatible with
General Relativity, and hence unite the General Relativity and Quantum
Mechanics in some range and puts forward a new idea of unification.


title:
Interplay of classical and "quantum" capacitance in a one dimensional
  array of Josephson junctions

abstract:
  Even in the absence of Coulomb interactions phase fluctuations induced by
quantum size effects become increasingly important in superconducting
nano-structures as the mean level spacing becomes comparable with the bulk
superconducting gap. Here we study the role of these fluctuations, termed
"quantum capacitance", in the phase diagram of a one-dimensional (1D) ring of
ultrasmall Josephson junctions (JJ) at zero temperature by using path integral
techniques. Our analysis also includes dissipation due to quasiparticle
tunneling and Coulomb interactions through a finite mutual and self
capacitance. The resulting phase diagram has several interesting features: A
finite quantum capacitance can stabilize superconductivity even in the limit of
only a finite mutual-capacitance energy which classically leads to breaking of
phase coherence. In the case of vanishing charging effects, relevant in cold
atom settings where Coulomb interactions are absent, we show analytically that
superfluidity is robust to small quantum finite-size fluctuations and identify
the minimum grain size for phase coherence to exist in the array. We have also
found that the renormalization group results are in some cases very sensitive
to relatively small changes of the instanton fugacity. For instance, a certain
combination of capacitances could lead to a non-monotonic dependence of the
superconductor-insulator transition on the Josephson coupling.


title: Sex-biased expression of microRNAs in Drosophila melanogaster

abstract:
  Most animals have separate sexes. The differential expression of gene
products, in particular that of gene regulators, is underlying sexual
dimorphism. Analyses of sex-biased expression have focused mostly in protein
coding genes. Several lines of evidence indicate that microRNAs, a class of
major gene regulators, are likely to have a significant role in sexual
dimorphism. This role has not been systematically explored so far. Here I study
the sex-biased expression pattern of microRNAs in the model species Drosophila
melanogaster. As with protein coding genes, sex biased microRNAs are associated
with the reproductive function. Strikingly, contrary to protein-coding genes,
male biased microRNAs are enriched in the X chromosome whilst female microRNAs
are mostly autosomal. I propose that the chromosomal distribution is a
consequence of high rates of de novo emergence, and a preference of new
microRNAs to be expressed in the testis. I also suggest that demasculinization
of the X chromosome may not affect microRNAs. Interestingly, female biased
microRNAs are often encoded within protein coding genes that are also expressed
in females. MicroRNAs with sex-biased expression do not preferentially target
sex-biased gene transcripts. These results strongly suggest that the sex-biased
expression of microRNAs is mainly a consequence of high rates of microRNA
emergence in the X (male bias) or hitch-hiked expression by host genes (female
bias).


title: Force-Gradient Nested Multirate Methods for Hamiltonian System

abstract:
  Force-gradient decomposition methods are used to improve the energy
preservation of symplectic schemes applied to Hamiltonian systems. If the
potential is composed of different parts with strongly varying dynamics, this
multirate potential can be exploited by coupling force-gradient decomposition
methods with splitting techniques for multi-time scale problems to further
increase the accuracy of the scheme and reduce the computational costs. In this
paper, we derive novel force-gradient nested methods and test them numerically.
Such methods can be used to increase the acceptance rate for the molecular
dynamics step of the Hybrid Monte Carlo algorithm (HMC) and hence improve its
computational efficiency.


title:
Black hole spin measurements through the relativistic precession model:
  XTE J1550-564

abstract:
  We present a systematic analysis of the complete set of observations of the
black hole (BH) binary XTE J1550-564 obtained by the Rossi X-ray Timing
Explorer. We study the fast time variability properties of the source and
determine the spin of the black hole through the relativistic precession model.
Similarly to what is observed in the BH binary GRO J1655-40, the frequencies of
the QPOs and broad band noise components match the general relativistic
frequencies of particle motion close to the compact object predicted by the
relativistic precession model. The combination of two simultaneously observed
quasi-periodic oscillation (QPO) frequencies together with the dynamical BH
mass from optical/infrared observations yields a spin equal to a = 0.34 +/-
0.01, consistent with previous determinations from X-ray spectroscopy. Based on
the derived BH parameters, the low frequency QPO emission radii vary from about
30 gravitational radii to the innermost stable orbit for this spin (about 5
gravitational radii), where they sharply disappear as observed for the case of
GRO J1655-40.


title:
BayMeth: Improved DNA methylation quantification for affinity capture
  sequencing data using a flexible Bayesian approach

abstract:
  DNA methylation (DNAme) is a critical component of the epigenetic regulatory
machinery and aberrations in DNAme patterns occur in many diseases, such as
cancer. Mapping and understanding DNAme profiles offers considerable promise
for reversing the aberrant states. There are several approaches to analyze
DNAme, which vary widely in cost, resolution and coverage. Affinity capture and
high-throughput sequencing of methylated DNA strike a good balance between the
high cost of whole genome bisulphite sequencing (WGBS) and the low coverage of
methylation arrays. However, existing methods cannot adequately differentiate
between hypomethylation patterns and low capture efficiency, and do not offer
flexibility to integrate copy number variation (CNV). Furthermore, no
uncertainty estimates are provided, which may prove useful for combining data
from multiple protocols or propagating into downstream analysis. We propose an
empirical Bayes framework that uses a fully methylated (i.e. SssI treated)
control sample to transform observed read densities into regional methylation
estimates. In our model, inefficient capture can be distinguished from low
methylation levels by means of larger posterior variances. Furthermore, we can
integrate CNV by introducing a multiplicative offset into our Poisson model
framework. Notably, our model offers analytic expressions for the mean and
variance of the methylation level and thus is fast to compute. Our algorithm
outperforms existing approaches in terms of bias, mean-squared error and
coverage probabilities as illustrated on multiple reference datasets. Although
our method provides advantages even without the SssI-control, considerable
improvement is achieved by its incorporation. Our method can be applied to
methylated DNA affinity enrichment assays (e.g MBD-seq, MeDIP-seq) and a
software implementation is available in the Bioconductor Repitools package.


title:
Various models of process of the learning, based on the numerical
  solution of the differential equations

abstract:
  The principles on which can be based computer model of process of training
are formulated. Are considered: 1) the unicomponent model, which is recognizing
that educational information consists of equal elements; 2) the multicomponent
model, which is considering that knowledge is assimilate with a various
strength, and on lesson weak knowledge becomes strong; 3) the generalized
multicomponent model which considers change of working capacity of the pupil
and various complexity of studied elements of a training material. Typical
results of imitating modeling of learning process are presented in article.


title:
The Mutual Interaction Between Population III Stars and
  Self-Annihilating Dark Matter

abstract:
  We use cosmological simulations of high-redshift minihalos to investigate the
effect of dark matter annihilation (DMA) on the collapse of primordial gas. We
numerically investigate the evolution of the gas as it assembles in a
Population III stellar disk. We find that when DMA effects are neglected, the
disk undergoes multiple fragmentation events beginning at ~ 500 yr after the
appearance of the first protostar. On the other hand, DMA heating and
ionization of the gas speeds the initial collapse of gas to protostellar
densities and also affects the stability of the developing disk against
fragmentation, depending on the DM distribution. We compare the evolution when
we model the DM density with an analytical DM profile which remains centrally
peaked, and when we simulate the DM profile using N-body particles (the 'live'
DM halo). When utilizing the analytical DM profile, DMA suppresses disk
fragmentation for ~ 3500 yr after the first protostar forms, in agreement with
earlier work. However, when using a 'live' DM halo, the central DM density peak
is gradually flattened due to the mutual interaction between the DM and the
rotating gaseous disk, reducing the effects of DMA on the gas, and enabling
secondary protostars of mass ~ 1 M_sol to be formed within ~ 900 yr. These
simulations demonstrate that DMA is ineffective in suppressing gas collapse and
subsequent fragmentation, rendering the formation of long-lived dark stars
unlikely. However, DMA effects may still be significant in the early collapse
and disk formation phase of primordial gas evolution.


title:
Short-Term Radio Variability and Parsec-Scale Structure in a Gamma-Ray
  Narrow-Line Seyfert 1 Galaxy 1H 0323+342

abstract:
  We made simultaneous single-dish and very long baseline interferometer (VLBI)
observations of a narrow-line Seyfert 1 galaxy (NLS1) 1H 0323+342, showing
gamma-ray activity revealed by Fermi/LAT observations. We found significant
variation of the total flux density at 8 GHz on the time scale of one month by
the single-dish monitoring. The total flux density varied by 5.5% in 32 days,
which is comparable to the gamma-ray variability time scale, corresponding to
the variability brightness temperature of $7.0 \times 10^{11}$ K. The source
consists of central and southeastern components on the parsec (pc) scale. The
flux of only the central component decreased in the same way as the total flux
density, indicating that the short-term radio variability, and probably the
gamma-ray emitting region, is associated with this component. From the VLBI
observations we obtained the brightness temperatures of greater than $(5.2 \pm
0.3) \times 10^{10}$ K, and derived the equipartition Doppler factor of greater
than 1.7, the variability Doppler factor of 2.2, and the 8 GHz radio power of
$10^{24.6}$ W Hz$^{-1}$. Combining them we conclude that acceleration of radio
jets and creation of high-energy particles are ongoing in the central engine,
and that the apparent very radio-loud feature of the source is due to the
Doppler-boosting effect, resulting in the intrinsic radio loudness to be an
order of magnitude smaller than the observed values. We also conclude that the
pc-scale jet represents recurrent activity from the the spectral fitting and
the estimated kinematic age of pc- and kpc-scale extended components with
different position angle.


title: Estimates on the zeros of $E_2$

abstract:
  We improve the results from [EBS10] about the Eisenstein series
$E_2(z)=1-24\sum_{n=1}^\infty \frac{nq^n}{1-q^n}$. In particular we show that
there exists exactly one (simple) zero in each Ford circle and give an
approximation to its location.


title: Marked empirical processes for non-stationary time series

abstract:
  Consider a first-order autoregressive process $X_i=\beta
X_{i-1}+\varepsilon_i,$ where $\varepsilon_i=G(\eta_i,\eta_{i-1},\ldots)$ and
$\eta_i,i\in\mathbb{Z}$ are i.i.d. random variables. Motivated by two important
issues for the inference of this model, namely, the quantile inference for
$H_0: \beta=1$, and the goodness-of-fit for the unit root model, the notion of
the marked empirical process
$\alpha_n(x)=\frac{1}{n}\sum_{i=1}^ng(X_i/a_n)I(\varepsilon_i\leq
x),x\in\mathbb{R}$ is investigated in this paper. Herein, $g(\cdot)$ is a
continuous function on $\mathbb{R}$ and $\{a_n\}$ is a sequence of
self-normalizing constants. As the innovation $\{\varepsilon_i\}$ is usually
not observable, the residual marked empirical process $\hat
{\alpha}_n(x)=\frac{1}{n}\sum_{i=1}^ng(X_i/a_n)I(\hat{\varepsilon}_i\l eq
x),x\in\mathbb{R},$ is considered instead, where
$\hat{\varepsilon}_i=X_i-\hat{\beta}X_{i-1}$ and $\hat{\beta}$ is a consistent
estimate of $\beta.$ In particular, via the martingale decomposition of
stationary process and the stochastic integral result of Jakubowski (Ann.
Probab. 24 (1996) 2141-2153), the limit distributions of $\alpha_n(x)$ and
$\hat{\alpha}_n(x)$ are established when $\{\varepsilon_i\}$ is a short-memory
process. Furthermore, by virtue of the results of Wu (Bernoulli 95 (2003)
809-831) and Ho and Hsing (Ann. Statist. 24 (1996) 992-1024) of empirical
process and the integral result of Mikosch and Norvai\v{s}a (Bernoulli 6 (2000)
401-434) and Young (Acta Math. 67 (1936) 251-282), the limit distributions of
$\alpha_n(x)$ and $\hat{\alpha}_n(x)$ are also derived when $\{\varepsilon_i\}$
is a long-memory process.


title: The purity of set-systems related to Grassmann necklaces

abstract:
  Studying the problem of quasicommuting quantum minors, Leclerc and Zelevinsky
introduced in 1998 the notion of weakly separated sets in $[n]:=\{1,\ldots,
n\}$. Moreover, they raised several conjectures on the purity for this
symmetric relation, in particular, on the Boolean cube $2^{[n]}$. In
0909.1423[math.CO] we proved these purity conjectures for the Boolean cube
$2^{[n]}$, the discrete Grassmanian ${[n]\choose r}$, and some other
set-systems. Oh, Postnikov, and Speyer in arxiv:1109.4434 proved the purity for
weakly separated collections inside a positroid which contain a Grassmann
necklace $\mathcal N$ defining the positroid. We denote such set-systems as
$\mathcal{I}nt(\mathcal N )$. In this paper we give an alternative (and
shorter) proof of the purity of $\mathcal{I}nt(\mathcal N )$ and present a
stronger result. More precisely, we introduce a set-system
$\mathcal{O}ut(\mathcal N )$ complementary to $\mathcal{I}nt(\mathcal N )$, in
a sense, and establish its purity. Moreover, we prove (Theorem~3) that these
two set-systems are weakly separated from each other. As a consequence of
Theorem~3, we obtain the purity of set-systems related to pairs of weakly
separated necklaces (Proposition 4 and Corollaries 1 and 2). Finally, we raise
a conjecture on the purity of both the interior and exterior of a generalized
necklace.


title: On characterizations of Bloch-type, Hardy-type and Lipschitz-type spaces

abstract:
  In this paper, we establish a Bloch-type growth theorem for generalized
Bloch-type spaces and discuss relationships between Dirichlet-type spaces and
Hardy-type spaces on certain classes of complex-valued functions. Then we
present some applications to non-homogeneous Yukawa PDEs. We also consider some
properties of the Lipschitz-type spaces on certain classes of complex-valued
functions. Finally, we will study a class of composition operators on these
spaces.


title: Spin liquid close to a quantum critical point in Na$_4$Ir$_3$O$_8$

abstract:
  Na$_4$Ir$_3$O$_8$ is a candidate material for a 3-dimensional quantum
spin-liquid on the hyperkagome lattice. We present thermodynamic measurements
of heat capacity $C$ and thermal conductivity $\kappa$ on high quality
polycrystalline samples of Na$_4$Ir$_3$O$_8$ down to $T = 500$ mK and $75$ mK,
respectively. Absence of long-range magnetic order down to $T = 75$ mK strongly
supports claims of a spin-liquid ground state. The constant magnetic
susceptibility $\chi$ below $T \approx 25$ K and the presence of a small but
finite linear-$T$ term in $C(T)$ suggest the presence of gapless spin
excitations. Additionally, the magnetic Gr$\ddot{\rm{u}}$neisen ratio shows a
divergence as $T \rightarrow 0$ K and a scaling behavior which clearly
demonstrates that Na$_4$Ir$_3$O$_8$ is situated close to a zero-field QCP.


title:
Chiral dynamics in a magnetic field from the functional renormalization
  group

abstract:
  We investigate the quark-meson model in a magnetic field using the exact
functional renormalization group equation beyond the local-potential
approximation. Our truncation of the effective action involves anisotropic wave
function renormalization for mesons, which allows us to investigate how the
magnetic field distorts the propagation of neutral mesons. Solving the flow
equation numerically, we find that the transverse velocity of mesons decreases
with the magnetic field at all temperatures, which is most prominent at zero
temperature. The meson screening masses and the pion decay constants are also
computed. The constituent quark mass is found to increase with magnetic field
at all temperatures, resulting in the crossover temperature that increases
monotonically with the magnetic field. This tendency is consistent with most
model calculations but not with the lattice simulation performed at the
physical point. Our work suggests that the strong anisotropy of meson
propagation may not be the fundamental origin of the inverse magnetic
catalysis.


title:
On the origin of the exponential decay of the Loschmidt echo in
  integrable systems

abstract:
  We address the time decay of the Loschmidt echo, measuring sensitivity of
quantum dynamics to small Hamiltonian perturbations, in one-dimensional
integrable systems. Using semiclassical analysis, we show that the Loschmidt
echo may exhibit a well-pronounced regime of exponential decay, alike the one
typically observed in quantum systems whose dynamics is chaotic in the
classical limit. We derive an explicit formula for the exponential decay rate
in terms of the spectral properties of the unperturbed and perturbed Hamilton
operators and the initial state. In particular, we show that the decay rate,
unlike in the case of the chaotic dynamics, is directly proportional to the
strength of the Hamiltonian perturbation. Finally, we compare our analytical
predictions against the results of a numerical computation of the Loschmidt
echo for a quantum particle moving inside a one-dimensional box with
Dirichlet-Robin boundary conditions, and find the two in good agreement.


title: Estimates for $p$-Laplace type equation in a limit case

abstract:
  We study some Dirichlet problem for a $p$--Laplacian type operator in the
setting of Orlicz--Zygmund space $L^q\log^{-\alpha}L(\Omega,\mathbb R^N)$, $q
>1$ and $\alpha>0$. More precisely, our aim is to establish which assuptions on
the parameter $\alpha>0$ lead to existence, uniqueness of the solution and
continuity of the associated nonlinear operator.


title: Tensor networks for Lattice Gauge Theories and Atomic Quantum Simulation

abstract:
  We show that gauge invariant quantum link models, Abelian and non-Abelian,
can be exactly described in terms of tensor networks states. Quantum link
models represent an ideal bridge between high-energy to cold atom physics, as
they can be used in cold-atoms in optical lattices to study lattice gauge
theories. In this framework, we characterize the phase diagram of a (1+1)-d
quantum link version of the Schwinger model in an external classical background
electric field: the quantum phase transition from a charge and parity ordered
phase with non-zero electric flux to a disordered one with a net zero electric
flux configuration is described by the Ising universality class.


title: de Sitter transitivity, conformal transformations and conservation laws

abstract:
  Minkowski spacetime is transitive under ordinary translations, a
transformation that do not have matrix representations. The de Sitter
spacetime, on the other hand, is transitive under a combination of translations
and proper conformal transformations, which do have a matrix representation.
Such matrix, however, is not by itself a de Sitter generator: it gives rise to
a conformal re-scaling of the metric, a transformation not belonging to the de
Sitter group, and in general not associated with diffeomorphisms in spacetime.
When dealing with variational principles and Noether's theorem in de Sitter
spacetime, therefore, it turns out necessary to regularise the transformations
in order to eliminate the conformal re-scaling of the metric.


title:
Fixing the Energy Scale in Scanning Tunneling Microscopy on
  Semiconductor Surfaces

abstract:
  In scanning tunneling experiments on semiconductor surfaces, the energy scale
within the tunneling junction is usually unknown due to tip-induced band
bending. Here, we experimentally recover the zero point of the energy scale by
combining scanning tunneling microscopy with Kelvin probe force spectroscopy.
With this technique, we revisit shallow acceptors buried in GaAs. Enhanced
acceptor-related conductance is observed in negative, zero, and positive
band-bending regimes. An Anderson-Hubbard model is used to rationalize our
findings, capturing the crossover between the acceptor state being part of an
impurity band for zero band bending, and the acceptor state being split off and
localized for strong negative or positive band bending, respectively.


title: Structural and electronic properties of the mu-phase Fe-Mo compounds

abstract:
  Structural (lattice parameters and sublattice occupancies) and electronic
(charge-density and electric field gradient) properties in a series of
compounds mu-Fe_(100-x)Mo_x were studied experimentally (X-ray diffraction and
Mossbauer spectroscopy) and theoretically (charge and spin self-consistent
KorringaKohnRostoker Green function method). The lattice parameters a and c
showed a linear increase with x while all five lattice sites were found to be
populated by both alloying elements: A and B predominantly by Fe atoms whereas
C and D by Mo atoms hardly depending on the composition. The population of Fe
atoms on the site E was ranging between ca. 50% at x=37.5 and ca. 20% at
x=44.5. Fe-site charge-density (isomer shift) and the electric field gradient
(quadrupole splitting, QS) were revealed to be characteristic of the lattice
site and both of them were almost x-independent. The difference in the
charge-density at Fe-atoms at the sites B (the highest value) and those at the
sites D (the lowest value) was estimated as equivalent to 0.18 electrons. The
average charge-density increases linearly with x. The largest QS-values were
those at the sites A and C, while the smallest ones at the site D.


title:
Broadband dielectric spectroscopy of Ba(Zr,Ti)O3: dynamics of relaxors
  and diffuse ferroelectrics

abstract:
  Broadband dielectric spectroscopy from Hz up to the infrared (IR) range and
temperature interval 10-300 K was carried out for xBaZrO3-(1-x)BaTiO3 (BZT-x, x
= 0.6, 0.7, 0.8) solid solution ceramics and compared with similar studies for
x = 0, 0.2, 0.4, 1 ceramics published recently (Phys. Rev. B 86, 014106
(2012)). Rather complex IR spectra without appreciable mode softening are
ascribed to Last-Slater transverse optic (TO) phonon eigenvector mixing and
possible two-mode mixed crystal behavior. Fitting of the complete spectral
range requires a relaxation in the 100 GHz range for all the samples. Below 1
GHz another relaxation appears, which is thermally activated and obeys the same
Arrhenius behavior for all the relaxor BZT samples. The frequently reported
Vogel-Fulcher behavior in BZT relaxors is shown to be an artifact of the
evaluation from the permittivity or loss vs. temperature dependences instead of
its evaluation from loss vs. frequency maxima. The relaxation is assigned to
local hopping of the off-centered Ti4+ ions in the frozen BTO clusters, whose
size is rather small and cannot grow on cooling. Therefore BZT is to be
considered as a dipolar glass rather than relaxor ferroelectric.


title: On dynamo action in the giant star Pollux : first results

abstract:
  We present preliminary results of a 3D MHD simulation of the convective
envelope of the giant star Pollux for which the rotation period and the
magnetic field intensity have been measured from spectroscopic and
spectropolarimetric observations. This giant is one of the first single giants
with a detected magnetic field, and the one with the weakest field so far. Our
aim is to understand the development and the action of the dynamo in its
extended convective envelope.


title:
The environmental dependence of neutral hydrogen in the GIMIC
  simulations

abstract:
  We use the Galaxies-Intergalactic Medium Interaction Calculation (GIMIC)
cosmological hydrodynamic simulation at z=0 to study the distribution and
environmental dependence of neutral hydrogen (HI) gas in the outskirts of
simulated galaxies. This gas can currently be probed directly in, for example,
Ly$\alpha$ absorption via the observation of background quasars. Radio
facilities, such as the Square Kilometre Array, will provide a complementary
probe of the diffuse HI in emission and will constrain the physics underpinning
the complex interplay between accretion and feedback mechanisms which affect
the intergalactic medium. We extract a sample of 488 galaxies from a
re-simulation of the average cosmic density GIMIC region. We estimate the
neutral hydrogen content of these galaxies and the surrounding intergalactic
medium within which they reside. We investigate the average HI radial profiles
by stacking the individual profiles according to both mass and environment. We
find high HI column densities at large impact parameters in group environments
and markedly lower HI densities for non-group galaxies. We suggest that these
results likely arise from the combined effects of ram pressure stripping and
tidal interactions present in group environments.


title: Approximate Least Squares

abstract:
  We present a novel iterative algorithm for approximating the linear least
squares solution with low complexity. After a motivation of the algorithm we
discuss the algorithm's properties including its complexity, and we present
theoretical results as well as simulation based performance results. We
describe the analysis of its convergence behavior and show that in the noise
free case the algorithm converges to the least squares solution.


title: Characterizations to the fractional Sobolev inequality

abstract:
  We characterize the fractional Sobolev inequality with fractional
isocapacitary and isoperimetric inequalities. We give a sufficient condition
and examples so that the fractional capacity of the closure of an open set is
bounded above by the fractional perimeter of its interior.


title: Distinct magnetic phase transition at the surface of an antiferromagnet

abstract:
  In the majority of magnetic systems the surface is required to order at the
same temperature as the bulk. In the present study, we report a distinct and
unexpected surface magnetic phase transition, uniquely at a lower temperature
than the N\'eel temperature. Employing grazing incidence X-ray resonant
magnetic scattering we have observed the near surface behavior of uranium
dioxide. UO$_2$ is a non-collinear, triple-q, antiferromagnet with the U ions
on an face-centered-cubic lattice. Theoretical investigations establish that at
the surface the energy increase, due to the lost bonds, reduces when the spins
near the surface rotate, gradually losing their normal to the surface
component. At the surface the lowest-energy spin configuration has a double-q
(planar) structure. With increasing temperature, thermal fluctuations saturate
the in-plane crystal field anisotropy at the surface, leading to soft
excitations that have ferromagnetic $XY$ character and are decoupled from the
bulk. The structure factor of a finite two-dimensional $XY$ model, fits the
experimental data well for several orders of magnitude of the scattered
intensity. Our results support a distinct magnetic transition at the surface in
the Kosterlitz-Thouless universality class.

categories: cond-mat.str-el cond-mat.mes-hall cond-mat.mtrl-sci cond-mat.stat-mech


title:
Dynamical behaviours in time-delay systems with delayed feedback and
  digitized coupling

abstract:
  We consider a network of delay dynamical systems connected in a ring via
unidirectional positive feedback with constant delay in coupling. For the
specific case of Mackey-Glass systems on the ring topology, we capture the
phenomena of amplitude death, isochronous synchronization and phase-flip
bifurcation as the relevant parameters are tuned. Using linear stability
analysis and master stability function approach, we predict the region of
amplitude death and synchronized states respectively in the parameter space and
study the nature of transitions between the different states. For a large
number of systems in the same dynamical configuration, we observe splay states,
mixed splay states and phase locked clusters. We extend the study to the case
of digitized coupling and observe that these emergent states still persist.
However, the sampling and quantization reduce the regions of amplitude death
and induce phase-flip bifurcation.


title:
A new integrable discrete generalized nonlinear Schrodinger equation and
  its reductions

abstract:
  A new integrable discrete system is constructed and studied, based on the
algebraization of the difference operator. The model is named the discrete
generalized nonlinear Schrodinger (GNLS) equation for which can be reduced to
classical discrete nonlinear Schrodinger (NLS) equation. To show the complete
integrability of the discrete GNLS equation, the recursion operator, symmetries
and conservation quantities are obtained. Furthermore, all of reductions for
the discrete GNLS equation are given and the discrete NLS equation is obtained
by one of the reductions. At the same time, the recursion operator and
symmetries of continuous GNLS equation are successfully recovered by its
corresponding discrete ones.


title: Efficiency of attack strategies on complex model and real-world networks

abstract:
  We investigated the efficiency of attack strategies to network nodes when
targeting several complex model and real-world networks. We tested 5 attack
strategies, 3 of which were introduced in this work for the first time, to
attack 3 model (Erdos and Renyi, Barabasi and Albert preferential attachment
network, and scale-free network configuration models) and 3 real networks
(Gnutella peer-to-peer network, email network of the University of Rovira i
Virgili, and immunoglobulin interaction network). Nodes were removed
sequentially according to the importance criterion defined by the attack
strategy. We used the size of the largest connected component (LCC) as a
measure of network damage. We found that the efficiency of attack strategies
(fraction of nodes to be deleted for a given reduction of LCC size) depends on
the topology of the network, although attacks based on the number of
connections of a node and betweenness centrality were often the most efficient
strategies. Sequential deletion of nodes in decreasing order of betweenness
centrality was the most efficient attack strategy when targeting real-world
networks. In particular for networks with power-law degree distribution, we
observed that most efficient strategy change during the sequential removal of
nodes.


title: Impact of asteroseismology on improving stellar ages determination

abstract:
  High precision photometry as performed by the CoRoT and Kepler satellites
on-board instruments has allowed to detect stellar oscillations over the whole
HR diagram. Oscillation frequencies are closely related to stellar interior
properties via the density and sound speed profiles, themselves tightly linked
with the mass and evolutionary state of stars. Seismic diagnostics performed on
stellar internal structure models allow to infer the age and mass of
oscillating stars. The accuracy and precision of the age determination depend
both on the goodness of the observational parameters (seismic and classical)
and on our ability to model a given star properly. They therefore suffer from
any misunderstanding of the physical processes at work inside stars (as
microscopic physics, transport processes...). In this paper, we recall some
seismic diagnostics of stellar age and we illustrate their efficiency in
age-dating the CoRoT target HD 52265.


title:
An analysis of Internet Banking in Portugal: the antecedents of mobile
  banking adoption

abstract:
  In recent years, mobile operations have gained wide popularity among
mainstream users, and banks tend to follow this trend. But are bank customers
ready to move forward? Mobile banking appears to be a natural extension of
Internet banking. Thus, to predict consumer decisions to adopt mobile banking,
it is useful to understand the pattern of adoption of Internet banking (IB).
This investigation seeks contribute to an expansion of the knowledge regarding
this matter by researching Portuguese consumers patterns and behaviors
concerning the acceptance and use intention of IB as a foundation for
establishing growth strategies of mobile banking. For data collection, we used
an online snowball process. The statistical treatment used included a factor
analysis in order to allow examination of the interrelationships between the
original variables. The analysis was made possible by developing a set of
factors that expresses the common traits between them. The results revealed
that the majority of respondents did not identify problems with the use of and
interaction with the IB service. The study generated some interesting findings.
First, the data generally supports the conceptual framework presented. However,
some points need to be made: trust and convenience, from all the elements
referenced in the literature as relevant from the client perspective, continue
to be a very important elements; the results did not support the paradigm that
the characteristics of individuals affect their behavior as consumers,
individual technological characteristics affect consumer adoption of IB
service; consumer perceptions about the IB service affect their use, as reveal
by the existence of three types of customers that show different practices and
perceptions of IB; and intention to use IB is dependent upon attitudes and
subjective norms regarding the use of IB.


title:
Non-perturbative Gauge-Higgs Unification: Symmetries and Order
  Parameters

abstract:
  We consider pure SU(N) gauge theories defined on an orbifold lattice,
analogous to the S^1/Z_2 gauge theory orbifolds of the continuum, which
according to the perturbative analysis do not have a Higgs phase.
Non-perturbatively the conclusion for N even is the opposite, namely that
spontaneous symmetry breaking does take place and some of the gauge bosons
become massive. We interpret this new, non-perturbative phenomenon both
mathematically and physically.


title:
Scenario Machine: fast radio bursts, short gamma-ray burst, dark energy
  and Laser Interferometer Gravitational-wave Observatory silence

abstract:
  We discuss the recently reported discovery of fast radio bursts (FRBs) in the
framework of the neutron star-neutron star (NS+NS) or neutron star-black hole
(NS+BH) binary merger model. We concentrate on what we consider to be an issue
of greatest importance: what is the NS merger rate given that the FRB rate
(1/1000 yr$^{-1}$ per galaxy) is inconsistent with gamma-ray burst rate as
discussed by Thornton and should be significantly higher. We show that there is
no discrepancy between NS merger rate and observed FRB rates in the framework
of the Scenario Machine population synthesis - for a kick velocity of 100-150
km s$^{-1}$ an average NS merger rate is 1/500-1/2000 yr$^{-1}$ per galaxy up
to z = 0.5-1. Based on the Scenario Machine NS merger rate estimates, we
discuss the lack of positive detections on the ground-based interferometers,
considering the Laser Interferometer Gravitational-wave Observatory.


title: The study of $U$-boson from $\pi^{0}$-meson decays at HIAF energy

abstract:
  Within the frame of LDM (light dark matter)-model, the LDM exchange particle
$U$-boson (with mass 10-100 MeV) can be produced from many meson decay process
so it attracts a lot of attention. Considering the merit of searching the
$U$-boson from $\pi ^{0}$ decay, the momentum spectra of light spin-1 vector
$U$-boson from decay channel $\pi ^{0}\rightarrow \gamma U$ and the energy
spectra of positron decay from $U\rightarrow e^{+}e^{-}$ at beam energy of 5-10
GeV are first presented by using a relativistic transport (ART) model.
Moreover,the feasibility and rationality of searching the $U$-boson in the
experiment at HIAF energy are discussed, which will be an important promotion
to understand and ultimately detect the $U$-boson, both in theory and
experiment.


title:
Algorithm for spectral response analysis of superconducting microwave
  transmission-line resonator

abstract:
  It has always been a challenge for researchers to efficiently and accurately
post process experimental data which is distorted by the noise. Superconducting
microwave devices e.g. resonators, directional filters, beam-splitters etc.
operate at frequency of several GHz to THz and temperatures well below critical
temperature (Tc) with few exceptions like transition edge sensors where devices
are operated at temperatures close to Tc. These devices are measured usually
with vector network analyser in terms of scattering parameters. Two kinds of
errors, systematic and drift can easily be removed from the measurements taken
with VNA. However, random errors are not easy to address and remove due to
their unpredictability and randomness. In this manuscript we will present an
algorithm to post process experimental data to cope with measurements that have
been corrupted or useful spectral response is buried in spurious signal. We
have developed a robust and efficient algorithm, implemented in MATLAB, to
detect peaks in spectral response, remove baseline and finally estimate
parameters of two-port superconductor resonator using an Improved Nelder-Mead
Method for unconstrained multidimensional least square minimization. The
algorithm has been successfully tested and verified by processing spectral
response of half wavelength microwave transmission-line resonator successfully
isolating resonator response from noisy background. We were able to compute
loaded quality factor, resonance frequency from response data with high
reproducibility even from those experimental data sets where resonance spikes
were hardly visible.


title:
Blind Turing-Machines: Arbitrary Private Computations from Group
  Homomorphic Encryption

abstract:
  Secure function evaluation (SFE) is the process of computing a function (or
running an algorithm) on some data, while keeping the input, output and
intermediate results hidden from the environment in which the function is
evaluated. This can be done using fully homomorphic encryption, Yao's garbled
circuits or secure multiparty computation. Applications are manifold, most
prominently the outsourcing of computations to cloud service providers, where
data is to be manipulated and processed in full confidentiality. Today, one of
the most intensively studied solutions to SFE is fully homomorphic encryption
(FHE). Ever since the first such systems have been discovered in 2009, and
despite much progress, FHE still remains inefficient and difficult to implement
practically. Similar concerns apply to garbled circuits and (generic)
multiparty computation protocols. In this work, we introduce the concept of a
blind Turing-machine, which uses simple homomorphic encryption (an extension of
ElGamal encryption) to process ciphertexts in the way as standard
Turing-machines do, thus achieving computability of any function in total
privacy. Remarkably, this shows that fully homomorphic encryption is indeed an
overly strong primitive to do SFE, as group homomorphic encryption with
equality check is already sufficient. Moreover, the technique is easy to
implement and perhaps opens the door to efficient private computations on
nowadays computing machinery, requiring only simple changes to well-established
computer architectures.


title: Selection rules for the Wheeler-DeWitt equation in quantum cosmology

abstract:
  Selection of physically meaningful solutions of the Wheeler-DeWitt equation
for the wavefunction in quantum cosmology, can be attained by a reduction of
the theory to the sector of true physical degrees of freedom and their
canonical quantization. The resulting physical wavefunction unitarily evolving
in the time variable introduced within this reduction can then be raised to the
level of the cosmological wavefunction in superspace of 3-metrics. We apply
this technique in several simple minisuperspace models and discuss both at
classical and quantum level physical reduction in {\em extrinsic} time -- the
time variable determined in terms of extrinsic curvature. Only this extrinsic
time gauge can be consistently used in vicinity of turning points and bounces
where the scale factor reaches extremum. Since the 3-metric scale factor is
canonically dual to extrinsic time variable, the transition from the physical
wavefunction to the wavefunction in superspace represents a kind of the
generalized Fourier transform. This transformation selects square integrable
solutions of the Wheeler-DeWitt equation, which guarantee Hermiticity of
canonical operators of the Dirac quantization scheme. Semiclassically this
means that wavefunctions are represented by oscillating waves in classically
allowed domains of superspace and exponentially fall off in classically
forbidden (underbarrier) regions. This is explicitly demonstrated in flat FRW
model with a scalar field having a constant negative potential and for the case
of phantom scalar field with a positive potential. The FRW model of a scalar
field with a vanishing potential does not lead to selection rules for solutions
of the Wheeler-DeWitt equation, but this does not violate Hermiticity
properties, because all these solutions are anyway of plane wave type and
describe cosmological dynamics without turning points and bounces.


title:
Coherent states on the Grassmannian $U(4)/U(2)^2$: Oscillator
  realization and bilayer fractional quantum Hall systems

abstract:
  Bilayer quantum Hall (BLQH) systems, which underlie a $U(4)$ symmetry,
display unique quantum coherence effects. We study coherent states (CS) on the
complex Grassmannian $\mathbb G_2^4=U(4)/U(2)^2$, orthonormal basis, $U(4)$
generators and their matrix elements in the reproducing kernel Hilbert space
$\mathcal H_\lambda(\mathbb G_2^4)$ of analytic square-integrable holomorphic
functions on $\mathbb G_2^4$, which carries a unitary irreducible
representation of $U(4)$ with index $\lambda\in\mathbb N$. A many-body
representation of the previous construction is introduced through an oscillator
realization of the $U(4)$ Lie algebra generators in terms of eight boson
operators. This particle picture allows us for a physical interpretation of our
abstract mathematical construction in the BLQH jargon. In particular, the index
$\lambda$ is related to the number of flux quanta bound to a bi-fermion in the
composite fermion picture of Jain for fractions of the filling factor $\nu=2$.
The simpler, and better known, case of spin-$s$ CS on the Riemann-Bloch sphere
$\mathbb{S}^2=U(2)/U(1)^2$ is also treated in parallel, of which Grassmannian
$\mathbb G_2^4$-CS can be regarded as a generalized (matrix) version.

categories: math-ph cond-mat.mes-hall math.MP quant-ph


title: Finite group actions on 4-manifolds with nonzero Euler characteristic

abstract:
  We prove that if $X$ is a compact, oriented, connected $4$-dimensional smooth
manifold, possibly with boundary, satisfying $\chi(X)\neq 0$, then there exists
an integer $C\geq 1$ such that any finite group $G$ acting smoothly and
effectively on $X$ has an abelian subgroup $A$ satisfying $[G:A]\leq C$,
$\chi(X^A)=\chi(X)$, and $A$ can be generated by at most $2$ elements.
Furthermore, if $\chi(X)<0$ then $A$ is cyclic. This proves, for any such $X$,
a conjecture of Ghys. We also prove an analogous result for manifolds of
arbitrary dimension and non-vanishing Euler characteristic, but restricted to
pseudofree actions.


title:
New Green function approach describing the ferromagnetic state in the
  simple Hubbard model

abstract:
  We consider a Hubbard model with occupation dependent hopping integrals.
Using the Hartree-Fock (H-F) approximation and the new Green function approach
with inter-site kinetic averages included, we analyze the influence of the
correlated hopping on ferromagnetic ordering. The influence of correlated
hopping on the nonlocal quasiparticle energies and corresponding k-dependent
spectral weights is included. In addition we obtain the shift of the spin bands
which is a major factor in creating spontaneous ferromagnetism. At some
parameters of the model the correlated hopping effect is strong enough to
achieve saturated ferromagnetism. This state may be obtained at the asymmetric
density of states (DOS) and the Fermi energy located in the region of large
spectral weight near the band edge. The results are compared with DMFT-Quantum
Monte Carlo calculations and with the Hubbard III approximation which includes
the correlated hopping effect.


title:
Hypercontractivity of a semi-Lagrangian scheme for Hamilton-Jacobi
  equations

abstract:
  The equivalence between logarithmic Sobolev inequalities and
hypercontractivity of solutions of Hamilton-Jacobi equations has been proved in
[5]. We consider a semi-Lagrangian approximation scheme for the Hamilton-Jacobi
equation and we prove that the solution of the discrete problem satisfies a
hypercontractivity estimate. We apply this property to obtain an error estimate
of the set where the truncation error is concentrated.


title:
On a symmetry of M\"uger's centralizer for the Drinfeld double of a
  semisimple Hopf algebra

abstract:
  In this paper we prove a formula that relates M\"uger's centralizer in the
category of representations of a factorizable Hopf algebra to the notion of
Hopf kernel of a representation of the dual Hopf algebra. Using this relation
we obtain a complete description for M\"uger's centralizer of some fusion
subcategories of the fusion category of finite dimensional representations of a
Drinfeld double of a semisimple Hopf algebra.


title:
Observations of a Hybrid Double-Streamer/Pseudostreamer in the Solar
  Corona

abstract:
  We report on the first observation of a single hybrid magnetic structure that
contains both a pseudostreamer and a double helmet streamer. This structure was
originally observed by the SWAP instrument aboard the PROBA2 satellite between
5 and 10~May~2013. It consists of a pair of filament channels near the south
pole of the sun. On the western edge of the structure, the magnetic morphology
above the filaments is that of a side-by-side double helmet streamer, with open
field between the two channels. On the eastern edge, the magnetic morphology is
that of a coronal pseudostreamer without the central open field. We
investigated this structure with multiple observations and modelling
techniques. We describe the topology and dynamic consequences of such a unified
structure.


title:
The Mdot - M* relation of pre-main sequence stars: a consequence of
  X-ray driven disc evolution

abstract:
  We analyse current measurements of accretion rates onto pre-main sequence
stars as a function of stellar mass, and conclude that the steep dependance of
accretion rates on stellar mass is real and not driven by selection/detection
threshold, as has been previously feared. These conclusions are reached by
means of statistical tests including a survival analysis which can account for
upper limits. The power-law slope of the Mdot-M* relation is found to be in the
range of 1.6-1.9 for young stars with masses lower than 1 Msun. The measured
slopes and distributions can be easily reproduced by means of a simple disc
model which includes viscous accretion and X-ray photoevaporation. We conclude
that the Mdot-M* relation in pre-main sequence stars bears the signature of
disc dispersal by X-ray photoevaporation, suggesting that the relation is a
straight- forward consequence of disc physics rather than an imprint of initial
conditions.


title:
Spin-orbit coupling and the static polarizability of single-wall carbon
  nanotubes

abstract:
  We calculate the static longitudinal polarizability of single-wall carbon
nanotubes in the long wavelength limit taking into account spin-orbit effects.
We use a four-orbital orthogonal tight-binding formalism to describe the
electronic states and the random phase approximation to calculate the
dielectric function. We study the role of both the Rashba as well as the
intrinsic spin-orbit interactions on the longitudinal dielectric response, i.e.
when the probing electric field is parallel to the nanotube axis. The
spin-orbit interaction modifies the nanotube electronic band dispersions, which
may especially result in a small gap opening in otherwise metallic tubes. The
bandgap size and state features, the result of competition between Rashba and
intrinsic spin-orbit interactions, result in drastic changes in the
longitudinal static polarizability of the system. We discuss results for
different nanotube types, and the dependence on nanotube radius and spin-orbit
couplings.


title:
Thermoelectric properties of doped small molecule organic semiconductor
  films

abstract:
  Doped films of organic small molecules are investigated with respect to their
thermoelectric properties. A variety of hosts and dopants, for both n and
p-doping, are compared. C$_{60}$ n-doped by Cr$_2$(hpp)$_4$ or o-MeO-DMBI-I are
found to be the most promising material systems with a maximum of ZT$_\text{M}$
= 0.069 at T$_\text{M}$ = 40{\deg}C, assuming a doping-independent thermal
conductivity due to phonon-based heat transport. This value is 16% of the
current record reported for optimized devices employing the doped polymer
PEDOT:PSS.


title:
Non-unitarity and non-reciprocity in scattering from real potentials in
  presence of confined non-linearity

abstract:
  Investigations of scattering in presence of non-linearity which have just
begun require the confinement of both the potential, $V(x)$, and the
non-linearity, $\gamma f(|\psi|)$. There could be two options for the
confinement. One is the finite support on $x \in [-L,L]$ and the other one is
on $x \in [0,L]$. Here, we consider real Hermitian potentials and report a
surprising disparate behaviour of these two types of confinements. We prove
that in the first option the symmetric potential enjoys reciprocity of both
reflectivity ($R$) and transmitivity ($T$) and their unitarity. More
interestingly, the asymmetry in $V(x)$ causes non-unitarity ($ R+T\ne 1$) and
the non-reciprocity (reciprocity) of $T (R)$. On the other hand, the second
option of confinement gives rise to an essential non-unitarity even when $V(x)$
is symmetric about a point in $[0,L]$. In the absence of symmetry there occurs
non-reciprocity of both $R$ and $T$.


title:
Benders, Nested Benders and Stochastic Programming: An Intuitive
  Introduction

abstract:
  This article aims to explain the Nested Benders algorithm for the solution of
large-scale stochastic programming problems in a way that is intelligible to
someone coming to it for the first time. In doing so it gives an explanation of
Benders decomposition and of its application to two-stage stochastic
programming problems (also known in this context as the L-shaped method), then
extends this to multi-stage problems as the Nested Benders algorithm. The
article is aimed at readers with some knowledge of linear and possibly
stochastic programming but aims to develop most concepts from simple principles
in an understandable way. The focus is on intuitive understanding rather than
rigorous proofs.


title:
Astrometric tests of General Relativity in the Solar System:
  mathematical and computational scenarios

abstract:
  We review the mathematical models available for relativistic astrometry,
discussing the different approaches and their accuracies in the context of the
modern experiments from space like Gaia and GAME, and we show how these models
can be applied to the real world, and their consequences from the mathematical
and numerical point of view, with specific reference to the case of Gaia, whose
launch is due before the end of the year.


title: Dynamics of a charged particle in a dissipative Fermi-Ulam model

abstract:
  The dynamics of a metallic particle confined between charged walls is
studied. One wall is fixed and the other moves smoothly and periodically in
time. Dissipation is considered by assuming a friction produced by the contact
between the particle and a rough surface. We investigate the phase space of the
simplified and complete versions of the model. Our results include (i)
coexistence of islands of regular motion with an attractor located at the low
energy portion of phase space in the complete model; and (ii) coexistence of
attractors with trajectories that present unlimited energy growth in the
simplified model.


title:
Infinite Determinantal Measures and The Ergodic Decomposition of
  Infinite Pickrell Measures I. Construction of infinite determinantal measures

abstract:
  This paper is the first in a series of three. The main result, Theorem 1.11,
gives an explicit description of the ergodic decomposition for infinite
Pickrell measures on spaces of infinite complex matrices. The main construction
is that of sigma-finite analogues of determinantal measures on spaces of
configurations. An example is the infinite Bessel point process, the scaling
limit of sigma-finite analogues of Jacobi orthogonal polynomial ensembles. The
statement of Theorem 1.11 is that the infinite Bessel point process (subject to
an appropriate change of variables) is precisely the ergodic decomposition
measure for infinite Pickrell measures.


title:
Local-field effects on the plasmon dispersion of two-dimensional
  transition metal dichalcogenides

abstract:
  Two-dimensional transition-metal dichalcogenides (TMDs) are gaining
increasing attention as alternative to graphene for their very high potential
in optoelectronics applications. Here we consider two prototypical metallic 2D
TMDs, NbSe$_2$ and TaS$_2$.
  Using a first-principles approach, we investigate the properties of the
localised intraband $d$ plasmon that cannot be modelled on the basis of the
homogeneous electron gas. Finally, we discuss the effects of the reduced
dimensionality on the plasmon dispersion through the interplay between
interband transitions and local-field effects. This result can be exploited to
tune the plasmonic properties of these novel 2D materials.


title:
No compelling cosmological models come out of magnetic universes which
  are based in nonlinear electrodynamics

abstract:
  Here we investigate the cosmic dynamics of Friedmann-Robertson-Walker
universes -- flat spatial sections -- which are driven by nonlinear
electrodynamics (NLED) Lagrangians. We pay special attention to the check of
the sign of the square sound speed since, whenever the latter quantity is
negative, the corresponding cosmological model is classically unstable against
small perturbations of the background energy density. Besides, based on
causality arguments, one has to require that the mentioned small perturbations
of the background should propagate at most at the local speed of light. We also
look for the occurrence of curvature singularities. Our results indicate that
several cosmological models which are based in known NLED Lagrangians, either
are plagued by curvature singularities of the sudden and/or big rip type, or
are violently unstable against small perturbations of the cosmological
background -- due to negative sign of the square sound speed -- or both. In
addition, causality issues associated with superluminal propagation of the
background perturbations may also arise.


title:
A determinant representation for generalized ballot and Fuss-Catalan
  numbers

abstract:
  In this note we introduce a determinant and then give its evaluating formula.
The determinant turns out to be a generalization of the well-known ballot and
Fuss-Catalan numbers, which is believed to be new. The evaluating formula is
proved by showing that the determinant coincides with the number of lattice
paths with (1,0), (0,1)-steps in the plane that stay below a boundary line of
rational slope.


title: Quiver Approach to Massive Gauge Bosons Beyond the Standard Model

abstract:
  We address the question of the possible existence of massive gauge bosons
beyond the $W^{\pm}$ and $Z^{0}$ of the standard model. Our intuitive and
aesthetic approach is based on quiver theory. Examples thereof arise, for
example, from compactification of the type IIB superstring on $AdS_5 \times
S_5/ Z_n$ orbifolds. We explore the quiver theory framework more generally than
string theory. The practical question is what gauge bosons to look for at the
upgraded LHC, in terms of color and electric charge, and of their couplings to
quarks and leptons. Axigluons and bileptons are favored.


title:
Coexistence of synchrony and incoherence in oscillatory media under
  nonlinear global coupling

abstract:
  We report a novel mechanism for the formation of chimera states, a peculiar
spatiotemporal pattern with coexisting synchronized and incoherent domains
found in ensembles of identical oscillators. Considering Stuart-Landau
oscillators we demonstrate that a nonlinear global coupling can induce this
symmetry breaking. We find chimera states also in a spatially extended system,
a modified complex Ginzburg-Landau equation. This theoretical prediction is
validated with an oscillatory electrochemical system, the electrooxidation of
silicon, where the spontaneous formation of chimeras is observed without any
external feedback control.


title: Tangent Lie algebra of derived Artin stacks

abstract:
  Since the work of Mikhail Kapranov in [Kap], it is known that the shifted
tangent complex $\mathbb{T}_X[-1]$ of a smooth algebraic variety $X$ is endowed
with a weak Lie structure. Moreover any complex of quasi-coherent sheaves on
$X$ is endowed with a weak Lie action of this tangent Lie algebra. This action
is given by the Atiyah class of $E$. We will generalize this result to (finite
enough) derived Artin stacks, without any smoothness assumption. This in
particular applies to (finite enough) singular schemes. This work uses tools of
both derived algebraic geometry and $\infty$-category theory.