title: A Herschel study of NGC 650

abstract:
  As part of the Herschel Guaranteed Time Key Project MESS (Mass loss of
Evolved StarS) we have imaged a sample of planetary nebulae. In this paper we
present the PACS and SPIRE images of the classical bipolar planetary nebula NGC
650. We used these images to derive a temperature map of the dust. We also
constructed a photoionization and dust radiative transfer model using the
spectral synthesis code Cloudy. To constrain this model, we used the PACS and
SPIRE fluxes and combined these with hitherto unpublished IUE and Spitzer IRS
spectra as well as various other data from the literature. The temperature map
combined with the photoionization model were used to study various aspects of
the central star, the nebula, and in particular the dust grains in the nebula.
The central star parameters are determined to be T_eff = 208 kK and L = 261
L_sol assuming a distance of 1200 pc. The stellar temperature is much higher
than previously published values. We confirm that the nebula is carbon-rich
with a C/O ratio of 2.1. The nebular abundances are typical for a type IIa
planetary nebula. With the photoionization model we determined that the grains
in the ionized nebula are large (assuming single-sized grains, they would have
a radius of 0.15 micron. Most likely these large grains were inherited from the
asymptotic giant branch phase. The PACS 70/160 micron temperature map shows
evidence for two radiation components heating the grains. The first component
is direct emission from the central star, while the second component is diffuse
emission from the ionized gas (mainly Ly alpha). We show that previous
suggestions that there is a photo-dissociation region surrounding the ionized
region are incorrect. The neutral material resides in dense clumps inside the
ionized region. These may also harbor stochastically heated very small grains
in addition to the large grains.


title: Optimal stopping and control near boundaries

abstract:
  We will investigate the value and inactive region of optimal stopping and
one-sided singular control problems by focusing on two fundamental ratios. We
shall see that these ratios unambiguously characterize the solution, although
usually only near boundaries. We will also study the well-known connection
between these problems and find it to be a local property rather than a global
one. The results are illustrated by a number of examples.


title:
Quasiparticle parameterization of meanfields, Galilei invariance and
  universal conserving response functions

abstract:
  The general possible form of meanfield parameterization in a running frame in
terms of current, energy and density functionals are examined under the
restrictions of Galilean invariance. It is found that only two
density-dependent parameters remain which are usually condensed in a
position-dependent effective mass and the selfenergy formed by current and
mass. The position-dependent mass induces a position-dependent local current
which is identified for different nonlinear frames. In a second step the
response to an external perturbation and relaxation towards a local equilibrium
is investigated. The response function is found to be universal in the sense
that the actual parameterization of the local equilibrium does not matter and
is eliminated from the theory due to the conservation laws. The explicit form
of the response with respect to density, momentum and energy is derived. The
compressibility sum rule as well as the sum rule by first and third-order
frequency moments are proved analytically to be fulfilled simultaneously. The
results are presented for Bose- or Fermi systems in one- two and three
dimensions.


title: A thread-parallel algorithm for anisotropic mesh adaptation

abstract:
  Anisotropic mesh adaptation is a powerful way to directly minimise the
computational cost of mesh based simulation. It is particularly important for
multi-scale problems where the required number of floating-point operations can
be reduced by orders of magnitude relative to more traditional static mesh
approaches.
  Increasingly, finite element and finite volume codes are being optimised for
modern multi-core architectures. Typically, decomposition methods implemented
through the Message Passing Interface (MPI) are applied for inter-node
parallelisation, while a threaded programming model, such as OpenMP, is used
for intra-node parallelisation. Inter-node parallelism for mesh adaptivity has
been successfully implemented by a number of groups. However, thread-level
parallelism is significantly more challenging because the underlying data
structures are extensively modified during mesh adaptation and a greater degree
of parallelism must be realised.
  In this paper we describe a new thread-parallel algorithm for anisotropic
mesh adaptation algorithms. For each of the mesh optimisation phases
(refinement, coarsening, swapping and smoothing) we describe how independent
sets of tasks are defined. We show how a deferred updates strategy can be used
to update the mesh data structures in parallel and without data contention. We
show that despite the complex nature of mesh adaptation and inherent load
imbalances in the mesh adaptivity, a parallel efficiency of 60% is achieved on
an 8 core Intel Xeon Sandybridge, and a 40% parallel efficiency is achieved
using 16 cores in a 2 socket Intel Xeon Sandybridge ccNUMA system.


title:
Noncommutative Chern-Simons theory and exotic geometry emerging from the
  lowest Landau level

abstract:
  We relate the collective dynamic internal geometric degrees of freedom to the
gauge fluctuations in $\nu=1/m$(m odd) fractional quantum Hall effects. In this
way, in the lowest Landau level, a highly nontrivial quantum geometry in
two-dimensional guiding center space emerges from these internal geometric
modes. Using the Dirac bracket method, we find that this quantum geometric
field theory is a topological non-commutative Chern-Simons theory.Topological
indices, such as the guiding center angular momentum (also called the shift)
and the guiding center spin, which characterize the fractional quantum Hall
(FQH) states besides the filling factor, are naturally defined. A
noncommutative K-matrix Chern-Simons theory is proposed as a generalization to
a large class of Abelian FQH topological orders.


title: Spin reorientation behavior in YMn1-xMxO3 (M = Ti, Fe, Ga; x = 0, 0.1)

abstract:
  The structural and magnetic properties of polycrystalline YMn1-xMxO3 (M = Ti,
Fe, Ga; x = 0, 0.1) have been studied by neutron powder diffraction and
magnetic measurements to probe the effect of Mn site doping on the frustration
behavior and magnetic structure of these compounds. The compounds are
isostructural and crystallize with hexagonal structure in P63cm space group. We
find that doping with these three ions, Ti4+ (d0), Fe3+ (d5) and Ga3+ (d10),
influences both the TN and magnetic structure, unlike other Mn-site dopants
reported previously. The magnetic structure of YMnO3 is described by
considering a linear combination of irreducible representations {\Gamma}3 and
{\Gamma}4 below TN ~ 75K and with decrease in temperature the ratio of
{\Gamma}3 and {\Gamma}4 changes. The mixing ratio of these two irreducible
representations remains constant on lowering of temperature in the Ga doped
compounds. The magnetic structure is modified on doping with nonmagnetic ion
Ti4+ (d0). It is described by the basis vectors of the irreducible
representation {\Gamma}2 with moment 2.3{\mu}B at 6 K. On doping with Fe3+ (d5)
the magnetic structure immediately below TN is explained by considering the
{\Gamma}3 irreducible representation. On further lowering of temperature, a
spin reorientation at ~ 35 K is observed. Below this temperature, the magnetic
structure of YMn0.9Fe0.1O3 is explained by considering {\Gamma}3 representation
with 51% mixing of {\Gamma}4. The ordered moments are found to be reduced from
the expected value for a Mn3+ ion in all these compounds indicating the
frustrated nature of these compounds. However, the frustration parameter, f is
significantly reduced in the case of Ti doped compound with {\Gamma}2
representation.


title: Holograghic Brownian motion in three dimensional G\"{o}del black hole

abstract:
  By using the AdS/CFT correspondence and G\"{o}del black hole background, we
study the dynamics of heavy quark under a rotating plasma. In that case we
follow Atmaja (JHEP 1304, 021, (2013)) about Brownian motion in BTZ black hole.
In this paper we receive some new results for the case of
$\alpha^{2}l^{2}\neq1$. This case, we must redefine the angular velocity of
string fluctuation. We obtain the time evolution of displacement square that
angular velocity and show that it behaves as a Brownian particle in
non-relativistic limit. In this plasma, it seems that relating the Brownian
motion with physical observables is rather a difficult work. But our results
match with Atmaja work in the limit $\alpha^{2}l^{2}\rightarrow1$.


title: Quasi-periodic Almost-collision Orbits in the Spatial Three-Body Problem

abstract:
  In a system of particles, quasi-periodic almost-collision orbits are
collisionless orbits along which two bodies become arbitrarily close to each
other -- the lower limit of their distance is zero but the upper limit is
strictly positive -- and which are quasi-periodic in a regularized system up to
a change of time. The existence of such orbits was shown in the restricted
planar circular three-body problem by A. Chenciner and J. Llibre, and later, in
the planar three-body problem by J. F\'ejoz. In the spatial three-body problem,
the existence of a set of positive measure of such orbits was predicted by C.
Marchal. In this article, we present a proof of this fact.


title: Permutation 2-groups I: structure and splitness

abstract:
  By a 2-group we mean a groupoid equipped with a weakened group structure. It
is called split when it is equivalent to the semidirect product of a discrete
2-group and a one-object 2-group. By a permutation 2-group we mean the 2-group
$\mathbb{S}ym(\mathcal{G})$ of self-equivalences of a groupoid $\mathcal{G}$
and natural isomorphisms between them, with the product given by composition of
self-equivalences. These generalize the symmetric groups $\mathsf{S}_n$, $n\geq
1$, obtained when $\mathcal{G}$ is a finite discrete groupoid.
  After introducing the wreath 2-product $\mathsf{S}_n\wr\wr\ \mathbb{G}$ of
the symmetric group $\mathsf{S}_n$ with an arbitrary 2-group $\mathbb{G}$, it
is shown that for any (finite type) groupoid $\mathcal{G}$ the permutation
2-group $\mathbb{S}ym(\mathcal{G})$ is equivalent to a product of wreath
2-products of the form $\mathsf{S}_n\wr\wr\
\mathbb{S}ym(\mathcal{B}\mathsf{G})$, where $\mathcal{B}\mathsf{G}$ is the
delooping of $\mathsf{G}$. This is next used to compute the homotopy invariants
of $\mathbb{S}ym(\mathcal{G})$ which classify it up to equivalence. In
particular, we prove that $\mathbb{S}ym(\mathcal{G})$ can be non-split, and
that the step from the trivial groupoid $\mathcal{B}\mathsf{1}$ to an arbitrary
one-object groupoid $\mathcal{B}\mathsf{G}$ is in fact the only source of
non-splitness. Various examples of permutation 2-groups are explicitly
computed, in particular the permutation 2-group of the underlying groupoid of a
(finite type) 2-group. It also follows from well known results about the
symmetric groups that the permutation 2-group of the groupoid of all finite
sets and bijections between them is equivalent to the direct product 2-group
$\mathbb{Z}_2[1]\times\mathbb{Z}_2[0]$, where $\mathbb{Z}_2[0]$ and
$\mathbb{Z}_2[1]$ stand for the group $\mathbb{Z}_2$ thought of as a discrete
and a one-object 2-group, respectively.


title: On the Riemann-Hilbert problem IV

abstract:
  With no criteria of the index type, it is proved the existence of a solution
for the Riemann-Hilbert problem in the fairly general setting of arbitrary
Jordan domains, measurable coefficients and measurable boundary data. The
theorem is formulated in terms of harmonic measure and principal asymptotic
values. It is also given the corresponding reinforced criterion for domains
with arbitrary rectifiable boundaries stated in terms of the natural parameter
and nontangential limits. Moreover, it is shown that the dimension of the
spaces of solutions is infinite.


title: Fifty shades of black

abstract:
  The paper proposes a new and systematic approach to the so-called black box
group methods in computational group theory. As the starting point of our
programme, we construct Frobenius maps on black box groups of untwisted Lie
type in odd characteristic and then apply them to black box groups X encrypting
groups (P)SL(2,q) in small odd characteristics. We propose an algorithm
constructing a black box field K isomorphic to F_q, and an isomorphism from
(P)SL(2,K) to X. The algorithm runs in time quadratic in the characteristic of
the underlying field and polynomial in log q.
  Due to the nature of our work we also have to discuss a few methodological
issues of the black box group theory.


title:
Fractionalized time reversal, parity and charge conjugation symmetry in
  topological superconductor: a possible origin of three generations of
  neutrinos and mass mixing

abstract:
  The existence of three generations of neutrinos(charged leptons/quarks) and
their mass mixing are deep mysteries of our universe. Recently, Majorana's
spirit returns in modern condensed matter physics -- in the context of
topological Majorana zero modes in certain classes of topological
superconductors(TSCs). In this paper, we attempt to investigate the topological
nature of the neutrino by assuming that a relativistic Majorana fermion can be
divided into four topological Majorana zero modes at cutoff energy scale, e.g.
planck scale. We begin with an exactly solvable $1$D lattice model which
realizes a $T^2=-1$ time reversal symmetry protected TSC, and show that a pair
of topological Majorana zero modes can realize a $T^4=-1$ time reversal
symmetry.Moreover, we find that a pair of topological Majorana zero modes can
also realize a $P^4=-1$ parity symmetry and even a nontrivial $\overline
C^4=-1$ charge conjugation symmetry. Next, we argue that the origin of three
generations of neutrinos(charged leptons and quarks) can be naturally explained
as three distinguishable ways of forming a pair of complex fermions(with
opposite spin polarizations) out of four topological Majorana zero modes,
characterized by the $T^4=-1$, $(TP)^4=-1$ and $(T \overline C)^4=-1$
fractionalized symmetries that each complex fermion carries at cutoff energy
scale. Finally, we use a semiclassical approach to compute the neutrino mass
mixing matrix at leading order(LO), e.g., in the absence of $CP$ violation
correction. We obtain $\theta_{12}=31.7^\circ, \theta_{23}=45^\circ$ and
$\theta_{13}=0^\circ$(the golden ratio pattern), which is consistent with an
$A_5$ flavor symmetry pattern. We further predict an exact mass ratio of the
three mass eigenstates of neutrinos with $m_1/m_3=m_2/m_3=3/\sqrt{5}$ and an
effective mass of neutrinoless double beta decay
$m_{0\nu\beta\beta}=m_1/\sqrt{5}$.


title:
Color screening potential at finite density in two-flavor lattice QCD
  with Wilson fermions

abstract:
  We investigate chemical-potential (\mu) dependence of static-quark free
energies in both the real and imaginary \mu regions, performing lattice QCD
simulations at imaginary \mu and extrapolating the results to the real \mu
region with analytic continuation. Lattice QCD calculations are done on a
16^{3}\times 4 lattice with the clover-improved two-flavor Wilson fermion
action and the renormalization-group improved Iwasaki gauge action.
Static-quark potential is evaluated from the Polyakov-loop correlation
functions in the deconfinement phase. As the analytic continuation, the
potential calculated at imaginary \mu=i\mu_{\rm I} is expanded into a
Taylor-expansion series of i\mu_{\rm I}/T up to 4th order and the pure
imaginary variable i\mu_{\rm I}/T is replaced by the real one \mu_{\rm R}/T. At
real \mu, the 4th-order term weakens \mu dependence of the potential sizably.
At long distance, all of the color singlet and non-singlet potentials tend to
twice the single-quark free energy, indicating that the interactions between
heavy quarks are fully color-screened for finite \mu. For both real and
imaginary \mu, the color-singlet q{\bar q} and the color-antitriplet qq
interaction are attractive, whereas the color-octet q{\bar q} and the
color-sextet qq interaction are repulsive. The attractive interactions have
stronger \mu/T dependence than the repulsive interactions. The color-Debye
screening mass is extracted from the color-singlet potential at imaginary \mu,
and the mass is extrapolated to real \mu by analytic continuation. The
screening mass thus obtained has stronger \mu dependence than the prediction of
the leading-order thermal perturbation theory at both real and imaginary \mu.


title:
3-D non-LTE radiative transfer effects in Fe I lines: II. Line formation
  in 3-D radiation hydrodynamic simulations

abstract:
  We investigate the effects of horizontal radiative transfer (RT) a NLTE on
important diagnostic iron lines in a realistic 3-D HD simulation. Using a
multi-level atom we compute and compare widely used Fe I line profiles at 3
different levels of approximation (3-D NLTE, 1-D NLTE, LTE). We find that the
influence of horizontal RT is of the same order of magnitude as that of NLTE,
although spatially more localized. Also, depending on the temperature of the
surroundings, horizontal RT is found to weaken or strengthen spectral lines.
Line depths and equivalent width may differ by up to 20% against the
corresponding LTE value if 3-D RT is applied. Residual intensity contrasts in
LTE are found to be larger than those in 3-D NLTE by up to a factor of two.
When compared to 1-D NLTE, we find that horizontal RT weakens the contrast by
up to 30% almost independently of the angle of line of sight. While the CLV of
the 1-D and 3-D NLTE contrasts are of similar form, the LTE contrast CLV shows
a different run. The determination of temperatures by 1-D NLTE inversions of
spatially resolved observations may produce errors of up to 200 K if one
neglects 3-D RT. We find a linear correlation between the intensity difference
of 1-D and 3-D NLTE and a simple estimate of the temperature in the horizontal
environment of the line formation region. This correlation could be used to
coarsely correct for the effects of horizontal RT in inversions done in 1-D
NLTE. Horizontal RT is less important if one considers spatially averaged line
profiles because local line strengthening and weakening occur with similar
frequency in our HD atmosphere. Thus, the iron abundance is underestimated by
0.012 dex if calculated using 1-D NLTE RT. Since effects of horizontal RT are
largest for spatially resolved quantities, the use of 3-D RT is particularly
important for the interpretation of high spatial resolution observations.


title: Peiffer Elements in the Moore Complex of a Bisimplicial Group

abstract:
  In this work, we explain `Peiffer pairings' in the Moore (bi)complex of a
bisimplicial group and give their applications for crossed modules and crossed
squares.


title: Embeddings of the complex ball into Siegel space

abstract:
  We study properties of a map from a certain unitary group in $n$ variables to
a related unitary group in $\binom{n}{k}$ variables. We explain how it gives
rise to a map between canonical models of Shimura varieties and we prove that
it extends to the ordinary locus of the integral model. Finally we extend
results of Satake on the endomorphism ring of a generic image point to positive
characteristics.


title: On quantum circuits employing roots of the Pauli matrices

abstract:
  The Pauli matrices are a set of three 2x2 complex Hermitian, unitary
matrices. In this article, we investigate the relationships between certain
roots of the Pauli matrices and how gates implementing those roots are used in
quantum circuits. Techniques for simplifying such circuits are given. In
particular, we show how those techniques can be used to find a circuit of
Clifford+T gates starting from a circuit composed of gates from the well
studied NCV library.


title:
Search for Rare Nuclear Decays with HPGe Detectors at the STELLA
  Facility of the LNGS

abstract:
  Results on the search for rare nuclear decays with the ultra low background
facility STELLA at the LNGS using gamma ray spectrometry are presented. In
particular, the best T1/2 limits were obtained for double beta processes in
96Ru and 104Ru. Several isotopes, which potentially decay through different
double beta decay channels, including also possible resonant double electron
captures, were investigated for the first time (156Dy, 158Dy, 184Os, 192Os,
190Pt, 198Pt). Search for resonant absorption of solar 7Li axions in a LiF
crystal gave the best limit for the mass of 7Li axions (< 8.6 keV). Rare alpha
decay of 190Pt to the first excited level of 186Os (Eexc = 137.2 keV) was
observed for the first time.


title: Large Shadows from Sparse Inequalities

abstract:
  The $d$-dimensional Goldfarb cube is a polytope with the property that all
its $2^d$ vertices appear on some \emph{shadow} of it (projection onto a
2-dimensional plane). The Goldfarb cube is the solution set of a system of 2d
linear inequalities with at most 3 variables per inequality. We show in this
paper that the $d$-dimensional Klee-Minty cube --- constructed from
inequalities with at most 2 variables per inequality --- also has a shadow with
$2^d$ vertices. In contrast, with one variable per inequality, the size of the
shadow is bounded by 2d.


title:
Symmetry-protected topological invariant and Majorana impurity states in
  time-reversal-invariant superconductors

abstract:
  We address the question of whether individual nonmagnetic impurities can
induce zero-energy states in time-reversal-invariant topological
superconductors, and define a class of symmetries which guarantee the existence
of such states for a specific value of the impurity strength. These symmetries
allow the definition of a position-space topological Z_2 invariant, which is
related to the standard bulk topological Z_2 invariant. Our general results are
applied to the time-reversal-invariant p-wave phase of the doped
Kitaev-Heisenberg model, where we demonstrate how a lattice of impurities can
drive a topologically trivial system into the nontrivial phase.


title: Bounding the Inefficiency of Altruism Through Social Contribution Games

abstract:
  We introduce a new class of games, called social contribution games (SCGs),
where each player's individual cost is equal to the cost he induces on society
because of his presence. Our results reveal that SCGs constitute useful
abstractions of altruistic games when it comes to the analysis of the robust
price of anarchy. We first show that SCGs are altruism-independently smooth,
i.e., the robust price of anarchy of these games remains the same under
arbitrary altruistic extensions. We then devise a general reduction technique
that enables us to reduce the problem of establishing smoothness for an
altruistic extension of a base game to a corresponding SCG. Our reduction
applies whenever the base game relates to a canonical SCG by satisfying a
simple social contribution boundedness property. As it turns out, several
well-known games satisfy this property and are thus amenable to our reduction
technique. Examples include min-sum scheduling games, congestion games, second
price auctions and valid utility games. Using our technique, we derive mostly
tight bounds on the robust price of anarchy of their altruistic extensions. For
the majority of the mentioned game classes, the results extend to the more
differentiated friendship setting. As we show, our reduction technique covers
this model if the base game satisfies three additional natural properties.


title:
On the leading term of asymptotics of the $n$ like-charged quantum
  particles scattering problem solution

abstract:
  An ansatz describing in terms of formal asymptotic decompositions a leading
term of asymptotics of the $n$ three-dimensional like-charged quantum particles
scattering problem solution is suggested. The description of the solution in
those asymptotic configurations in which it was known earlier (for example,
$n=3$), coincides with the previously known constructions
\cite{BBK,z1,am92,BL2,KL}. It is shown that the Schredinger equation
discrepancy for the suggested ansatz decreases faster than the potential
uniformly in all angle variables at infinity in configuration space. An
assumption is made about the structure of the leading term of the asymptotics
of the scattering problem solution related to the $n$ three-dimensional quantum
particles interacting by a broad class of slowly decreasing pair potentials.


title: Towards a regularity theory for integral Menger curvature

abstract:
  We generalize the notion of integral Menger curvature introduced by Gonzalez
and Maddocks by decoupling the powers in the integrand. This leads to a new
two-parameter family of knot energies $intM^{p,q}$. We classify finite-energy
curves in terms of Sobolev-Slobodeckij spaces. Moreover, restricting to the
range of parameters leading to a sub-critical Euler-Lagrange equation, we prove
existence of minimizers within any knot class via a uniform bi-Lipschitz bound.
Consequently, $intM^{p,q}$ is a knot energy in the sense of O'Hara. Restricting
to the non-degenerate sub-critical case, a suitable decomposition of the first
variation allows to establish a bootstrapping argument that leads to
$C^{\infty}$-smoothness of critical points.


title: On a normed version of a Rogers-Shephard type problem

abstract:
  A translation body of a convex body is the convex hull of two of its
translates intersecting each other. In the 1950s, Rogers and Shephard found the
extremal values, over the family of $n$-dimensional convex bodies, of the
maximal volume of the translation bodies of a given convex body. In our paper,
we introduce a normed version of this problem, and for the planar case,
determine the corresponding quantities, with one exception, for the four types
of volumes regularly used in the literature: Busemann, Holmes-Thompson, and
Gromov's mass and mass*. We examine the problem also for higher dimensions, and
for centrally symmetric convex bodies.


title: Duality of singular paths for (2,3,5)-distributions

abstract:
  We show a duality which arises from distributions of Cartan type, having
growth (2, 3, 5), from the view point of geometric control theory. In fact we
consider the space of singular (or abnormal) paths on a given five dimensional
space endowed with a Cartan distribution, which form another five dimensional
space with a cone structure. We regard the cone structure as a control system
and show that the space of singular paths of the cone structure is naturally
identified with the original space. Moreover we observe an asymmetry on this
duality in terms of singular paths.


title:
X-ray crystal structure analysis and the Ru valence of Ba4Ru3O10 single
  crystals

abstract:
  We present the single-crystalline x-ray diffraction study on the Ba4Ru3O10
consisting of the corner-shared Ru3O12 trimers. The crystal structure is
re-determined from 78 to 300 K across an antiferromagnetic transition at 105 K.
The orthorhombic symmetry (Cmca, space group No. 64) is preserved at all
temperatures measured. This structure presents exceptionally long Ru-O
distances characterized by a significant distribution within the Ru3O12 trimer.
A bond valence sum calculation suggests that the charge disproportionation
within the Ru3O12 trimer emerges even at room temperature, which we ascribe to
molecular orbital formation in the Ru3O12 trimer, as supported by recent
theoretical calculations. Based on the analyzed crystal structure, the
electronic states and the nature of the phase transition at 105 K are
discussed.


title: Asymptotically log Fano varieties

abstract:
  Motivated by the study of Fano type varieties we define a new class of log
pairs that we call asymptotically log Fano varieties and strongly
asymptotically log Fano varieties. We study their properties in dimension two
under an additional assumption of log smoothness, and give a complete
classification of two dimensional strongly asymptotically log smooth log Fano
varieties. Based on this classification we formulate an asymptotic logarithmic
version of Calabi's conjecture for del Pezzo surfaces for the existence of
K\"ahler--Einstein edge metrics in this regime. We make some initial progress
towards its proof by demonstrating some existence and non-existence results,
among them a generalization of Matsushima's result on the reductivity of the
automorphism group of the pair, and results on log canonical thresholds of
pairs. One by-product of this study is a new conjectural picture for the small
angle regime and limit which reveals a rich structure in the asymptotic regime,
of which a folklore conjecture concerning the case of a Fano manifold with an
anticanonical divisor is a special case.


title:
Analyticity of the self-energy in total momentum of an atom coupled to
  the quantized radiation field

abstract:
  We study a neutral atom with a non-vanishing electric dipole moment coupled
to the quantized electromagnetic field. For a sufficiently small dipole moment
and small momentum, the one-particle (self-) energy of an atom is proven to be
a real-analytic function of its momentum. The main ingredient of our proof is a
suitable form of the Feshbach-Schur spectral renormalization group.


title: Stability Results for Simple Traffic Models Under PI-Regulator Control

abstract:
  This paper provides necessary conditions and sufficient conditions for the
(global) Input-to-State Stability property of simple uncertain
vehicular-traffic network models under the effect of a PI-regulator. Local
stability properties for vehicular-traffic networks under the effect of
PI-regulator control are studied as well: the region of attraction of a locally
exponentially stable equilibrium point is estimated by means of Lyapunov
functions. All obtained results are illustrated by means of simple examples.


title:
Time resolved spectral analysis of the prompt emission of long gamma ray
  bursts with GeV Emission

abstract:
  We make a detailed time resolved spectroscopy of bright long gamma ray bursts
(GRBs) which show significant GeV emissions (GRB 080916C, GRB 090902B, and GRB
090926A). In addition to the standard Band model, we also use a model
consisting of a blackbody and a power-law to fit the spectra. We find that for
the latter model there are indications for an additional soft component in the
spectra. While previous studies have shown that such models are required for
GRB 090902B, here we find that a composite spectral model consisting of two
black bodies and a power law adequately fit the data of all the three bright
GRBs. We investigate the evolution of the spectral parameters and find several
generic interesting features for all three GRBs, like a) temperatures of the
black bodies are strongly correlated to each other, b) flux in the black body
components are strongly correlated to each other, c) the temperatures of the
black body trace the profile of the individual pulses of the GRBs, and d) the
characteristics of the power law component like the spectral index and the
delayed onset bear a close similarity to the emission characteristics in the
GeV regions. We discuss the implications of these results to the possibility of
identifying the radiation mechanisms during the prompt emission of GRBs.


title: Linearizability with Ownership Transfer

abstract:
  Linearizability is a commonly accepted notion of correctness for libraries of
concurrent algorithms. Unfortunately, it assumes a complete isolation between a
library and its client, with interactions limited to passing values of a given
data type. This is inappropriate for common programming languages, where
libraries and their clients can communicate via the heap, transferring the
ownership of data structures, and can even run in a shared address space
without any memory protection. In this paper, we present the first definition
of linearizability that lifts this limitation and establish an Abstraction
Theorem: while proving a property of a client of a concurrent library, we can
soundly replace the library by its abstract implementation related to the
original one by our generalisation of linearizability. This allows abstracting
from the details of the library implementation while reasoning about the
client. We also prove that linearizability with ownership transfer can be
derived from the classical one if the library does not access some of data
structures transferred to it by the client.


title:
The substitution effects on electronic structure of iron selenide
  superconductors

abstract:
  The influence of a partial substitution with S, Te, Co, Ni and Cu atoms on
the electronic structure of the FeSe superconductor has been investigated
within the density functional theory. The results of the supercell calculations
reveal distinct changes of electronic structures of the substituted FeSe
systems, which can be responsible for their superconducting properties. The
replacement of Se atoms by Te or S ones yields imperfect nesting between the
holelike and electronlike Fermi surface (FS) sheets, which enhances magnetic
fluctuations responsible for superconducting pairing, thus leading to higher
values of the superconducting critical temperatures. Meanwhile, the
substitutions with transition-metal atoms for iron sites make more substantial
changes of the FSs topology, since the holelike cylinders shrink at the cost of
an enlargement of the electronlike ones. Thus, the superconducting pairing,
driven by the nesting between these sheets, weakens and superconductivity
disappears for a small percentage of dopants. The results support the idea of
spin-fluctuation mediated superconductivity in iron chalcogenides.


title: Coding and Compression of Three Dimensional Meshes by Planes

abstract:
  The present paper suggests a new approach for geometric representation of 3D
spatial models and provides a new compression algorithm for 3D meshes, which is
based on mathematical theory of convex geometry. In our approach we represent a
3D convex polyhedron by means of planes, containing only its faces. This allows
not to consider topological aspects of the problem (connectivity information
among vertices and edges) since by means of the planes we construct the
polyhedron uniquely. Due to the fact that the topological data is ignored this
representation provides high degree of compression. Also planes based
representation provides a compression of geometrical data because most of the
faces of the polyhedron are not triangles but polygons with more than three
vertices.


title: Direct integrals of matrices

abstract:
  It is shown that each linear operator on a separable Hilbert space which
generates a finite type I von Neumann algebra has, up to unitary equivalence, a
unique representation as a direct integral of inflations of mutually unitary
inequivalent irreducible matrices. This leads to a simplification of the
so-called prime (or central) decomposition and the multiplicity theory for such
operators. The concept of so-called p-isomorphisms between special classes of
such operators is discussed. All results are formulated in more general
settings; that is, for tuples of closed densely defined operators affiliated
with finite type I von Neumann algebras.


title: Anisotropic Heisenberg Model on Core-Shell Structured Nanotube Geometry

abstract:
  The effect of the anisotropy in the exchange interaction on the critical
temperature and the order parameter of the anisotropic Heisenberg model on a
core-shell structured nanotube geometry has been investigated. As a
formulation, effective field theory with the differential operator technique
and decoupling approximation within the 4-spin cluster (EFT-4) has been used.
The variation of the critical temperature with the anisotropy in the exchange
interaction has been obtained. Besides, suitability of the effective field
theory in small clusters as a formulation for the Heisenberg nanotube has been
discussed and it is concluded that minimum size of the cluster is 4-spin
cluster, which can give the correct critical description of the system.


title: Vectorial Radio Interferometry with LOPES 3D

abstract:
  One successful detection technique for high-energy cosmic rays is based on
the radio signal emitted by the charged particles in an air shower. The LOPES
experiment at Karlsruhe Institute of Technology, Germany, has made major
contributions to the evolution of this technique. LOPES was reconfigured
several times to improve and further develop the radio detection technique. In
the latest setup LOPES consisted of 10 tripole antennas. With this, LOPES 3D
was the first cosmic ray experiment measuring all three vectorial field
components at once and thereby gaining the full information about the electric
field vector. We present an analysis based on the data taken with special focus
on the benefits of a direct measurement of the vertical polarization component.
We demonstrate that by measuring all polarization components the detection and
reconstruction efficiency is increased and noisy single channel data can be
reconstructed by utilising the information from the other two channels of one
antenna station.


title: Schmidt modes and entanglement of biphoton polarization qutrits

abstract:
  Polarization features and entanglement of biphoton polarization qutrits are
briefly outlined. Schmidt modes of qutrits are found analytically and in a
general form by the method different from the standard one and based on the
original approach of Erhard Schmidt (1906)


title: Quantitative Stratification and the Regularity of Harmonic Map Flow

abstract:
  In this paper, we prove estimates and quantitative regularity results for the
harmonic map flow. First, we consider H^1_loc-maps u defined on a parabolic
ball P\subset M\times R and with target manifold N, that have bounded
Dirichlet-energy and Struwe-energy. We define a quantitative stratification,
which groups together points in the domain into quantitative weakly singular
strata S^j_{\eta,r}(u) according to the number of approximate symmetries of u
at certain scales, and prove that their tubular neighborhoods have small
volume, namely Vol(T_r(\cS^j_{\eta,r}(u))< Cr^{m+2-j-\eps}. In particular, this
generalizes the known Hausdorff estimate dim S^j(u)< j for the weakly singular
strata of suitable weak solutions of the harmonic map flow. As an application,
specializing to Chen-Struwe solutions with target manifolds that do not admit
certain harmonic and quasi-harmonic spheres, we obtain refined Minkowski
estimates for the singular set. This generalizes a result of Lin-Wang. We also
obtain L^p-estimates for the reciprocal of the regularity scale. The results
are analogous to our results for mean curvature flow that we recently proved.


title: Tree-level Correlators of scalar and vector fields in AdS/CFT

abstract:
  Extending earlier results by Paulos, we discuss further the use of the
embedding formalism and Mellin transform in the calculation of tree-level
correlators of scalar and vector fields in AdS/CFT. We present an iterative
procedure that builds amplitudes by sewing together lower-point off-shell
diagrams. Both scalar and vector correlators are shown to be given in terms of
Mellin amplitudes. We apply the procedure to the explicit calculation of
three-, four- and five-point correlators.


title:
Fluctuation in e-mail sizes weakens power-law correlations in e-mail
  flow

abstract:
  Power-law correlations have been observed in packet flow over the Internet.
The possible origin of these correlations includes demand for Internet
services. We observe the demand for e-mail services in an organization, and
analyze correlations in the flow and the sequence of send requests using a
Detrended Fluctuation Analysis (DFA). The correlation in the flow is found to
be weaker than that in the send requests. Four types of artificial flow are
constructed to investigate the effects of fluctuations in e-mail sizes. As a
result, we find that the correlation in the flow originates from that in the
sequence of send requests. The strength of the power-law correlation decreases
as a function of the ratio of the standard deviation of e-mail sizes to their
average.


title:
Coercivity weighted Langevin magnetisation; A new approach to interpret
  superparamagnetic and nonsuperparamagnetic behaviour in single domain
  magnetic nanoparticles

abstract:
  Superparamagnetism (SPM) is an attractive material property often appearing
in nanoscaled single domain (SD) configurations. However, not all SD particles
are superparamagnetic, which depends on a few parameters including material
type, temperature, measurement time and magneto crystalline anisotropy. The
non-linear magnetisation response of magnetic particles can be interpreted by
classical Langevin approach but its applicability is limited to pure SD-SPM
behaviour. The classical Langevin equation lacks parameters to account for
possible remanence and coercivity in SD regime, resultantly, the SD-nonSPM
possibility is left untreated. To solve this issue, we propose a new model by
including SD coercivity parameters in classical Langevin equations. The new
model 1) combines steady or time varying magnetisation dynamics and temperature
or particle size dependent coercivity and 2) helps to calculate coercivity
compensated magnetisations and susceptibilities directly. The model covers full
spectrum of SD diameters and defines the switching between superparamagnetic
and non-superparamagnetic states more precisely.


title:
A complete determination of New Physics parameters in leptonic decays of
  $\mathbf{B_{s}^0}$

abstract:
  Recently LHCb has measured the branching ratio of the rare decay of
$B_s^0\rightarrow \mu^+ \mu^- $ as $2.9^{+1.1}_{-1.0} \times10^{-9}$ which is
at par with the predicted standard model (SM) value. This result does not
predict the absence of new physics (NP), rather it confines the NP
parameter-space in a more stringent fashion. In this paper we have used the
general loop level Hamiltonian to constrain the parameter space for the NP
couplings for $B_s^0\rightarrow \mu^+ \mu^- $ from the experimental branching
ratio. Using the available parameter space for these couplings, we have
explored the angular analysis of the cascade decay of $B^0_{s}\to \tau^+\tau^-
\to (\rho^+\bar{\nu}_\tau)_{\tau^+}(\pi^{-}\nu_{\tau})_{\tau^-} \to ((\pi^+
\pi^0)_{\rho^+}\bar{\nu}_\tau)_{\tau^+}(\pi^{-}\nu_{\tau})_{\tau^-}$. This
analysis shows presence of NP can be identified by the angular analysis and
also shows how to isolate the NP contribution from the SM. We believe that in
future with the reduced error in the branching ratio measurement and better
$\tau$ cone reconstruction technique we will be able to probe NP signal using
this angular analysis.


title: Damage accumulation in quasi-brittle fracture

abstract:
  The strength of quasi-brittle materials depends on the ensemble of defects
inside the sample and on the way damage accumulates before failure. Using large
scale numerical simulations of the random fuse model, we investigate the
evolution of the microcrack distribution that is directly related to the
strength distribution and its size effects. We show that the broadening of the
distribution tail originates from the dominating microcracks in each sample and
is related to a tendency of crack coalescence that increases with system size.
We study how the observed behavior depends on the disorder present in the
sample.


title:
Normal property, Jamenson property, CHIP and linear regularity for an
  infinite system of convex sets in Banach spaces

abstract:
  In this paper, we study different kinds of normal properties for infinite
system of arbitrarily many convex sets in a Banach space and provide the dual
characterization for the normal property in terms of the extended Jamenson
property for arbitrarily many weak*-closed convex cones in the dual space.
Then, we use the normal property and the extended Jamenson property to study
CHIP, strong CHIP and linear regularity for the infinite case of arbitrarily
many convex sets and establish equivalent relationship among these properties.
In particular, we extend main results in [3] on normal property, Jamenson
property, CHIP and linear regularity for finite system of convex sets in a
Hilbert space to the infinite case of arbitrarily many convex sets in Banach
space setting.


title: Numerical study of the generalised Klein-Gordon equations

abstract:
  In this study, we discuss an approximate set of equations describing water
wave propagating in deep water. These generalized Klein-Gordon (gKG) equations
possess a variational formulation, as well as a canonical Hamiltonian and
multi-symplectic structures. Periodic travelling wave solutions are constructed
numerically to high accuracy and compared to a seventh-order Stokes expansion
of the full Euler equations. Then, we propose an efficient pseudo-spectral
discretisation, which allows to assess the stability of travelling waves and
localised wave packets.


title:
Sub-arcsecond high sensitivity measurements of the DG~Tau jet with
  e-MERLIN

abstract:
  We present very high spatial resolution deep radio continuum observations at
5 GHz (6 cm) made with e-MERLIN of the young stars DG Tau A and B. Assuming it
is launched very close (~=1 au) from the star, our results suggest that the DG
Tau A outflow initially starts as a poorly focused wind and undergoes
significant collimation further along the jet (~=50 au). We derive jet
parameters for DG Tau A and find an initial jet opening angle of 86 degrees
within 2 au of the source, a mass-loss rate of 1.5x10^-8 solar masses/yr for
the ionised component of the jet, and the total ejection/accretion ratio to
range from 0.06-0.3. These results are in line with predictions from MHD
jet-launching theories.


title:
Comparison of LOPES data and CoREAS simulations using a full detector
  simulation (ICRC2013)

abstract:
  The LOPES experiment at the Karlsruhe Institute of Technology, Germany, has
been measuring radio emission of air showers for almost 10 years. For a better
understanding of the emission process a detailed comparison of data with
simulations is necessary. This is possible using a newly developed detector
simulation including all LOPES detector components. After propagating a
simulated event through this full detector simulation a standard LOPES like
event file is written. LOPES data and CoREAS simulations can then be treated
equally and the same analysis software can be applied to both. This gives the
opportunity to compare data and simulations directly. Furthermore, the standard
analysis software can be used with simulations which provide the possibility to
check the accuracy regarding reconstruction of air shower parameters. We point
out the advantages and present first results using such a full LOPES detector
simulation. A comparison of LOPES data and the Monte Carlo code CoREAS based on
an analysis using this detector simulation is shown.


title: Why is the Conclusion of the GERDA Experiment not Justified ?

abstract:
  The first results of the GERDA double beta experiment in Gran Sasso were
recently presented. They are fully consistent with the Heidelberg-Moscow
experiment, but because of its low statistics cannot proof anything at this
moment. It is no surprise that the statistics is still far from being able to
test the signal claimed by the HEIDELBERG-MOSCOW experiment. The energy
resolution of the coaxial detectors is a factor of 1.5 worse than in the
HEIDELBERG-MOSCOW experiment. The original goal of background reduction to
10^{-2}counts/kgykeV, or by an order of magnitude compared to the
HEIDELBERG-MOSCOW experiment, has not been reached. The background is only a
factor 2.3 lower if we refer it to the experimental line width, i.e. in units
counts/kgy energy resolution.
  With pulse shape analysis (PSA) the background in the HEIDELBERG-MOSCOW
experiment around Q_{\beta\beta} is 4x10^{-3} counts/kgykeV
\cite{HVKK-IVK-MPhLA2006}, which is a factor of 4 (5 referring to the line
width) lower than that of GERDA with pulse shape analysis.
  The amount of enriched material used in the GERDA measurement is 14.6kg, only
a factor of 1.34 larger than that used in the HM experiment. The background
model is oversimplified and not yet adequate. It is not shown that the lines of
their background can be identified. GERDA has to continue the measurement
further ~5years, until they can responsibly present an understood background.
The present half life limit presented by GERDA of T_{1/2}^{0\nu} > 2.1 x
10^{25} y (90% confidence level, i.e. 1.6sigma)) is still lower than the
half-life of T_{1/2}^{0\nu} = 2.23^{{+0.44}_{-0.31}} x 10^{25} y
\cite{HVKK-IVK-MPhLA2006} determined in the HEIDELBERG-MOSCOW experiment.


title: Picard numbers of quintic surfaces

abstract:
  We solve the Picard number problem for complex quintic surfaces by proving
that every number between 1 and 45 occurs as Picard number of a quintic surface
over the rationals. Our main technique consists in arithmetic deformations of
Delsarte surfaces, but we also use K3 surfaces and wild automorphisms.


title:
New Superconducting Toroidal Magnet System for IAXO, the International
  AXion Observatory

abstract:
  Axions are hypothetical particles that were postulated to solve one of the
puzzles arising in the standard model of particle physics, namely the strong CP
(Charge conjugation and Parity) problem. The new International AXion
Observatory (IAXO) will incorporate the most promising solar axions detector to
date, which is designed to enhance the sensitivity to the axion-photon coupling
by one order of magnitude beyond the limits of the current state-of-the-art
detector, the CERN Axion Solar Telescope (CAST). The IAXO detector relies on a
high-magnetic field distributed over a very large volume to convert solar
axions into X-ray photons. Inspired by the successful realization of the ATLAS
barrel and end-cap toroids, a very large superconducting toroid is currently
designed at CERN to provide the required magnetic field. This toroid will
comprise eight, one meter wide and twenty one meter long, racetrack coils. The
system is sized 5.2 m in diameter and 25 m in length. Its peak magnetic field
is 5.4 T with a stored energy of 500 MJ. The magnetic field optimization
process to arrive at maximum detector yield is described. In addition,
materials selection and their structure and sizing has been determined by force
and stress calculations. Thermal loads are estimated to size the necessary
cryogenic power and the concept of a forced flow supercritical helium based
cryogenic system is given. A quench simulation confirmed the quench protection
scheme.


title: Multi-Colour Quantum Metrology with Entangled Photons

abstract:
  Entangled photons can be used to make measurements with an accuracy beyond
that possible with classical light. While most implementations of quantum
metrology have used states made up of a single colour of photons, we show that
entangled states of two colours can show supersensitivity to optical phase and
path-length by using a photonic crystal fibre source of photon pairs inside an
interferometer. This setup is relatively simple and robust to experimental
imperfections. We demonstrate sensitivity beyond the standard quantum limit and
show super-resolved interference fringes using entangled states of two, four,
and six photons.


title: Direct observation of atomic diffusion in warm rubidium ensembles

abstract:
  We present a robust method for measuring the diffusion coefficients of warm
atoms in buffer gases. Using optical pumping, we manipulate the atomic spin in
a thin cylinder inside the cell. Then we observe the spatial spread of
optically pumped atoms in time using a camera, which allows us to determine the
diffusion coefficient. As an example, we demonstrate measurements of diffusion
coefficients of rubidium in neon, krypton and xenon acting as buffer gases. We
have determined the normalized (273 K, 760 Torr) diffusion coefficients to be
0.18$\pm$0.03 cm$^2$/s for neon, 0.07$\pm$0.01 cm$^2$/s for krypton, and
0.052$\pm$0.006 cm$^2$/s for xenon.


title: "Smile"-gap in the density of states of a cavity between superconductors

abstract:
  The density of Andreev levels in a normal metal ($N$) in contact with two
superconductors ($S$) is known to exhibit an induced minigap related to the
inverse dwell time. We predict a small secondary gap just below the
superconducting gap edge---a feature that has been overlooked so far in
numerous studies of the density of states in $S-N-S$ structures. In a generic
structure with $N$ being a chaotic cavity, the secondary gap is the widest at
zero phase bias. It closes at some finite phase bias, forming the shape of a
"smile". Asymmetric couplings give even richer gap structures near the phase
difference \pi. All the features found should be amendable to experimental
detection in high-resolution low-temperature tunneling spectroscopy.


title: Confined structures of least bending energy

abstract:
  In this paper we study a constrained minimization problem for the Willmore
functional. For prescribed surface area we consider smooth embeddings of the
sphere into the unit ball. We evaluate the dependence of the the minimal
Willmore energy of such surfaces on the prescribed surface area and prove
corresponding upper and lower bounds. Interesting features arise when the
prescribed surface area just exceeds the surface area of the unit sphere. We
show that (almost) minimizing surfaces cannot be a $C^2$-small perturbation of
the sphere. Indeed they have to be nonconvex and there is a sharp increase in
Willmore energy with a square root rate with respect to the increase in surface
area.


title: Polarization bispectrum for measuring primordial magnetic fields

abstract:
  We examine the potential of polarization bispectra of the cosmic microwave
background (CMB) to constrain primordial magnetic fields (PMFs). We compute all
possible bispectra between temperature and polarization anisotropies sourced by
PMFs and show that they are weakly correlated with well-known local-type and
secondary ISW-lensing bispectra. From a Fisher analysis it is found that, owing
to E-mode bispectra, in a cosmic-variance-limited experiment the expected
uncertainty in the amplitude of magnetized bispectra is 80% improved in
comparison with an analysis in terms of temperature auto-bispectrum alone. In
the $\mathit{Planck}$ or the proposed PRISM experiment cases, we will be able
to measure PMFs with strength 2.6 or 2.2 nG. PMFs also generate bispectra
involving B-mode polarization, due to tensor-mode dependence. We also find that
the B-mode bispectrum can reduce the uncertainty more drastically and hence
PMFs comparable to or less than 1 nG may be measured in a PRISM-like
experiment.


title: Predator-Prey Interactions, Age Structures and Delay Equations

abstract:
  A general framework for age-structured predator-prey systems is introduced.
Individuals are distinguished into two classes, juveniles and adults, and
several possible interactions are considered. The initial system of partial
differential equations is reduced to a system of (neutral) delay differential
equations with one or two delays. Thanks to this approach, physically correct
models for predator-prey with delay are provided. Previous models are
considered and analysed in view of the above results. A Rosenzweig-MacArthur
model with delay is presented as an example.


title:
Detecting filamentary pattern in the cosmic web: a catalogue of
  filaments for the SDSS

abstract:
  The main feature of the spatial large-scale galaxy distribution is its
intricate network of galaxy filaments. This network is spanned by the galaxy
locations that can be interpreted as a three-dimensional point distribution.
The global properties of the point process can be measured by different
statistical methods, which, however, do not describe directly the structure
elements. The morphology of the large scale structure, on the other hand, is an
important property of the galaxy distribution. Here we apply an object point
process with interactions (the Bisous model) to trace and extract the
filamentary network in the presently largest galaxy redshift survey, the Sloan
Digital Sky Survey (SDSS). We search for filaments in the galaxy distribution
that have a radius of about 0.5 Mpc/h. We divide the detected network into
single filaments and present a public catalogue of filaments. We study the
filament length distribution and show that the longest filaments reach the
length of 60 Mpc/h. The filaments contain 35-40% of the total galaxy luminosity
and they cover roughly 5-8% of the total volume, in good agreement with N-body
simulations and previous observational results.


title: Dark Matter

abstract:
  I give a review of the development of the concept of dark matter. The dark
matter story passed through several stages from a minor observational puzzle to
a major challenge for theory of elementary particles. Modern data suggest that
dark matter is the dominant matter component in the Universe, and that it
consists of some unknown non-baryonic particles. Dark matter is the dominant
matter component in the Universe, thus properties of dark matter particles
determine the structure of the cosmic web.


title: Discrete tunneling in granulated substances and other similar mediums

abstract:
  Work is devoted to physics of current transport in a wide class of the
hetero-phase granulated mediums and similar systems with set of metal or
semi-conductor granules, quantum dots or potential wells in which the exit from
Coulomb blockade tunneling regime can be not observable because of irreversible
breakdown and destruction of structure of medium. Such systems also concern and
the condensed mediums with short distanced atoms of transition elements. In
article for small and average electric fields the analytical decision of a
stationary problem of discrete electronic transport through a chain of as much
as big number of metal granules in area Coulomb tunneling blockade is
performed. It is deduced the exponential law of growth of a current with
electric field in such granulated systems. The characteristic feature of
discrete tunneling in such medium is the volt-ampere characteristic type I
exp(V/(N+1)kT) with great value N>> 1. Examples of application of the theory
for explanation of current transport in porous silicon, synthesised by ionic
implantation of nitrogen in silicon layers of nitride of silicon or glass like
amorphous semiconductors are resulted.


title: Convergence Rates for Inverse Problems with Impulsive Noise

abstract:
  We study inverse problems F(f) = g with perturbed right hand side g^{obs}
corrupted by so-called impulsive noise, i.e. noise which is concentrated on a
small subset of the domain of definition of g. It is well known that
Tikhonov-type regularization with an L^1 data fidelity term yields
significantly more accurate results than Tikhonov regularization with classical
L^2 data fidelity terms for this type of noise. The purpose of this paper is to
provide a convergence analysis explaining this remarkable difference in
accuracy. Our error estimates significantly improve previous error estimates
for Tikhonov regularization with L^1-fidelity term in the case of impulsive
noise. We present numerical results which are in good agreement with the
predictions of our analysis.


title: Distinguished minimal toplogical lassos

abstract:
  A classical result in distance based tree-reconstruction characterizes when
for a distance $D$ on some finite set $X$ there exist a uniquely determined
dendrogram on $X$ (essentially a rooted tree $T=(V,E)$ with leaf set $X$ and no
degree two vertices but possibly the root and an edge weighting $\omega:E\to
\mathbb R_{\geq 0}$) such that the distance $D_{(T,\omega)}$ induced by
$(T,\omega)$ on $X$ is $D$. Moreover, algorithms that quickly reconstruct
$(T,\omega)$ from $D$ in this case are known. However in many areas where
dendrograms are being constructed such as Computational Biology not all
distances on $X$ are always available implying that the sought after dendrogram
need not be uniquely determined anymore by the available distances with regards
to topology of the underlying tree, edge-weighting, or both. To better
understand the structural properties a set $\cL\subseteq {X\choose 2}$ has to
satisfy to overcome this problem, various types of lassos have been introduced.
Here, we focus on the question of when a lasso uniquely determines the topology
of a dendrogram's underlying tree, that is, it is a topological lasso for that
tree. We show that any set-inclusion minimal topological lasso for such a tree
$T$ can be transformed into a 'distinguished' minimal topological lasso $\cL$
for $T$, that is, the graph $(X,\cL)$ is a claw-free block graph. Furthermore,
we characterize such lassos in terms of the novel concept of a cluster marker
map for $T$ and present results concerning the heritability of such lassos in
the context of the subtree and supertree problems.


title: A note on a series containing the Laguerre polynomials

abstract:
  Expressions for the summation of a new series involving the Laguerre
polynomials are obtained in terms of generalized hypergeometric functions.
These results provide alternative, and in some cases simpler, expressions to
those recently obtained in the literature.


title:
Stability Analysis of the Lugiato-Lefever Model for Kerr Optical
  Frequency Combs. Part I: Case of Normal Dispersion

abstract:
  We propose a detailed stability analysis of the Lugiato-Lefever model for
Kerr optical frequency combs in whispering gallery mode resonators pumped in
the normal dispersion regime. We analyze the spatial bifurcation structure of
the stationary states depending on two parameters that are experimentally
tunable, namely the pump power and the cavity detuning. Our study demonstrates
that the non-trivial equilibria play an important role in this bifurcation map,
as their associated eigenvalues undergo critical bifurcations that are
foreshadowing the existence of localized spatial structures. In particular, we
show that in the normal dispersion regime, dark cavity solitons can emerge in
the system, and thereby generate a Kerr comb. We also show how these solitons
can coexist in the resonator as long as they do not interact with each other.
The Kerr combs created by these (sets of) dark solitons are also analyzed, and
their stability is discussed as well.


title: Matrix-Valued Little q-Jacobi Polynomials

abstract:
  Matrix-valued analogues of the little q-Jacobi polynomials are introduced and
studied. For the 2x2-matrix-valued little q-Jacobi polynomials explicit
expressions for the orthogonality relations, Rodrigues formula, three-term
recurrence relation and their relation to matrix-valued q-hypergeometric series
and the scalar-valued little q-Jacobi polynomials are presented. The study is
based on a matrix-valued q-difference operator, which is a q-analogue of
Tirao's matrix-valued hypergeometric differential operator.


abstract:
  A translation from Russian of the work of R.R. Kamalian "Interval colorings
of complete bipartite graphs and trees", Preprint of the Computing Centre of
the Academy of Sciences of Armenia, Yerevan, 1989. (Was published by the
decision of the Academic Council of the Computing Centre of the Academy of
Sciences of Armenian SSR and Yerevan State University from 7.09.1989).


title:
Stability Analysis of the Lugiato-Lefever Model for Kerr Optical
  Frequency Combs. Part II: Case of Anomalous Dispersion

abstract:
  We present a stability analysis of the Lugiato-Lefever model for Kerr optical
frequency combs in whispering gallery mode resonators pumped in the anomalous
dispersion regime. This article is the second part of a research work whose
first part was devoted to the regime of normal dispersion, and was presented in
ref. \cite{Part_I}. The case of anomalous dispersion is indeed the most
interesting from the theoretical point of view, because of the considerable
variety of dynamical behaviors that can be observed. From a technological point
of view, it is also the most relevant because it corresponds to the regime
where Kerr combs are predominantly generated, studied, and used for different
applications. In this article, we analyze the connection between the spatial
patterns and the bifurcation structure of the eigenvalues associated to the
various equilibria of the system. The bifurcation map evidences a considerable
richness from a dynamical standpoint. We study in detail the emergence of
super- and sub-critical Turing patterns in the system. We determine the areas
were bright isolated cavity solitons emerge, and we show that soliton molecules
can emerge as well. Very complex temporal patterns can actually be observed in
the system, where solitons (or soliton complexes) co-exist with or without
mutual interactions. Our investigations also unveil the mechanism leading to
the phenomenon of breathing solitons. Two routes to chaos in the system are
identified, namely a route via the so called secondary combs, and another via
soliton breathers. The Kerr combs corresponding to all these temporal patterns
are analyzed in detail, and a discussion is led about the possibility to gain
synthetic comprehension of the observed spectra out of the dynamical complexity
of the system.


title: Phonon Interference Effects in Molecular Junctions

abstract:
  We study coherent phonon transport through organic, \pi-conjugated molecules.
Using first principles calculations and Green's function methods, we find that
the phonon transmission function in cross-conjugated molecules, like
meta-connected benzene, exhibits destructive quantum interference features very
analogous to those observed theoretically and experimentally for electron
transport in similar molecules. The destructive interference features observed
in four different cross-conjugated molecules significantly reduce the thermal
conductance with respect to linear conjugated analogues. Such control of the
thermal conductance by chemical modifications could be important for
thermoelectric applications of molecular junctions.


title:
Bremsstrahlung and black hole production from collisions of
  ultra-boosted particles at non-zero impact parameter

abstract:
  The collision of two massless, gravitationally interacting, point-like
massless particles, boosted to the speed of light, colliding with an impact
parameter b is being investigated. The collision takes place in four space-time
flat dimensional background. A perturbative scheme is employed and the
corrections to the energy momentum tensor and to the metric are computed and
closed form formulas are provided. This includes the back-reaction on the
metric after the collision. Including such corrections suggests that the
tracelessness of the initial stress tensors of the colliding particles is
preserved during and after the collision. The necessity for introducing an
impact parameter in the perturbative treatment is highlighted and the breaking
of the underlying perturbative approach at b = 0 is motivated. In addition, the
energy radiated in the form of gravitational bremsstrahlung radiation is
discussed while an example from gravitational-waves collision is being studied.


title:
Tetraquarks, hadronic molecules, meson-meson scattering and disconnected
  contributions in lattice QCD

abstract:
  There are generally two types of Wick contractions in lattice QCD
calculations of a correlation function --- connected and disconnected ones. The
disconnected contribution is difficult to calculate and noisy, thus it is often
neglected. In the context of studying tetraquarks, hadronic molecules and
meson-meson scattering, we show that whenever there are both connected and
singly disconnected contractions, the singly disconnected part gives the
leading order contribution, and thus should never be neglected. As an explicit
example, we show that information about the scalar mesons sigma, f0(980),
a0(980) and kappa will be lost when neglecting the disconnected contributions.


title: Low energy singularities in the ground state of fermionic superfluids

abstract:
  We analyze the effects of order parameter fluctuations on the ground state of
fully gapped charge-neutral fermionic superfluids. The Goldstone mode
associated with the spontaneously broken symmetry leads to a problem of coupled
singularities in $d \leq 3$ dimensions. We derive a minimal set of one-loop
renormalization group equations which fully captures the interplay of the
singularities. The flow equations are based on a symmetry conserving truncation
of a scale dependent effective action. We compute the low energy behavior of
longitudinal, transverse and mixed order parameter correlations, and their
impact on the fermionic gap. We demonstrate analytically that cancellations
protecting the Goldstone mode are respected by the flow, and we present a
numerical solution of the flow equations for the two-dimensional attractive
Hubbard model.


title:
Biophysical modelling of the effects of inhaled radon progeny on the
  bronchial epithelium for the estimation of the relationships applied in the
  two stage clonal expansion model of carcinogenesis

abstract:
  There is a considerable debate between research groups applying the two stage
clonal expansion model for lung cancer risk estimation, whether radon exposure
affects initiation and transformation or promotion. The objective of the
present study is to quantify the effects of radon progeny on these stages with
biophysical models. For this purpose, numerical models of mutation induction
and clonal growth were applied in order to estimate how initiation,
transformation and promotion rates depend on tissue dose rate. It was found
that rates of initiation and transformation increase monotonically with dose
rate, while effective promotion rate decreases with time, but increases in a
supralinear fashion with dose rate. Despite the uncertainty of the results due
to the lack of experimental data, present study suggests that effects of radon
exposure on both mutational events and clonal growth are significant, and
should be considered in epidemiological analyses applying mathematical models
of carcinogenesis.


title:
Phase transition for the vacant set left by random walk on the giant
  component of a random graph

abstract:
  We study the simple random walk on the giant component of a supercritical
Erd\H{o}s-R\'enyi random graph on $n$ vertices, in particular the so-called
vacant set at level $u$, the complement of the trajectory of the random walk
run up to a time proportional to $u$ and $n$. We show that the component
structure of the vacant set exhibits a phase transition at a critical parameter
$u_{\star}$: For $u<u_{\star}$ the vacant set has with high probability a
unique giant component of order $n$ and all other components small, of order at
most $\log^{7}n$, whereas for $u>u_{\star}$ it has with high probability all
components small. Moreover, we show that $u_{\star}$ coincides with the
critical parameter of random interlacements on a Poisson-Galton-Watson tree,
which was identified in [Tas10].


title: Operations on t-structures and perverse coherent sheaves

abstract:
  The notions of consistent pairs and consistent chains of t-structures are
introduced. A theorem that two consistent chains of t-structures generate a
distributive lattice is proven. The technique developed is then applied to the
pairs of chains obtained from the standard t-structure on the derived category
of coherent sheaves and the dual t-structure by means of the shift functor.
This yields a family of t-structures whose hearts are known as perverse
coherent sheaves.


title: Quantization of horizon entropy and the thermodynamics of spacetime

abstract:
  This is a review of my work published in the papers [1-4]. It offers a more
detailed discussion of the results than what was given in the published papers
and it links my results to some conclusions recently made by other people. It
also offers some new arguments for the conclusions previously made. The
fundamental idea of this work is that the semi-classical quantization of the
black hole entropy, as suggested by Bekenstein [5], holds (at least)
generically for the spacetime horizons. We support this conclusion by two
separate arguments: 1. we generalize Bekenstein's lower bound on the horizon
area transition to much larger class of horizons than only the black hole
horizon, 2. we obtain the same entropy spectra via the asymptotic quasi-normal
frequencies of some particular spherically symmetric multi-horizon spacetimes,
(in the way proposed by Maggiore [6]). The main result of this paper supports
the conclusions made by other people in [7,8], but uses different arguments.


title:
Predictions for BAO distance estimates from the cross-correlation of the
  Lyman-alpha forest and redshifted 21-cm emission

abstract:
  We investigate the possibility of using the cross-correlation of the
Lyman-alpha forest and redshifted 21-cm emission to detect the baryon acoustic
oscillation (BAO). The standard Fisher matrix formalism is used to determine
the accuracy with which it will be possible to measure cosmological distances
using this signal. Earlier predictions indicate that it will be possible to
measure the dilation factor D_V with 1.9 % accuracy at z=2.5 from the BOSS
Lyman-alpha forest auto-correlation. In this paper we investigate if it is
possible to improve the accuracy using the cross-correlation.
  We use a simple parametrization of the Lyman-alpha forest survey which very
loosely matches some properties of BOSS and predicts delta D_V/D_V = 2.0 % for
the auto-correlation at z=2.5. For the redshifted 21-cm observations we
consider individual antennas of size 2 m * 2 m distributed such that the
baselines within 250 m are uniformly sampled. It is assumed that the
observations span z=2 to 3 and covers the 10,000 deg^2 sky coverage of BOSS. We
find that for 2 years of observation with an array of 2,000 antennas, the
cross-correlation is 1.7 times more sensitive than the Lyman-alpha forest
auto-correlation. The cross-correlation is 2.7 times more sensitive than the
auto-correlation if we have 4,000 antennas and 4 years of observation. In
conclusion, we find that it is possible to significantly increase the accuracy
of the distance estimates by considering the cross-correlation signal.


title:
Oscillating spin-orbit interaction as a source of spin-polarized wave
  packets in two-terminal nanoscale devices

abstract:
  Ballistic transport through nanoscale devices with time-dependent Rashba-type
spin-orbit interaction (SOI) can lead to spin-polarized wave packets that
appear even for completely unpolarized input. The SOI that oscillates in a
finite domain generates density and spin polarization fluctuations that leave
the region as propagating waves. Particularly, spin polarization has space and
time dependence even in regions without SOI. Our results are based on an
analytic solution of the time-dependent Schr\"odinger equation. The relevant
Floquet quasi-energies that are obtained appear in the energy spectrum of both
the transmitted and reflected waves.


title:
New results on $\nu_\mu \to \nu_\tau$ appearance with the OPERA
  experiment in the CNGS beam

abstract:
  The OPERA neutrino experiment is designed to perform the first observation of
neutrino oscillations in direct appearance mode in the $\nu_\mu \to \nu_\tau$
channel, via the detection of the $\tau$-leptons created in charged current
$\nu_\tau$ interactions. The detector, located in the underground Gran Sasso
Laboratory, consists of an emulsion/lead target with an average mass of about
1.2 kt, complemented by electronic detectors. It is exposed to the CERN
Neutrinos to Gran Sasso beam, with a baseline of 730 km and a mean energy of 17
GeV. The observation of the first $\nu_\tau$ candidate event and the analysis
of the 2008-2009 neutrino sample have been reported in previous publications.
This work describes substantial improvements in the analysis and in the
evaluation of the detection efficiencies and backgrounds using new simulation
tools. The analysis is extended to a sub-sample of 2010 and 2011 data,
resulting from an electronic detector-based pre-selection, in which an
additional $\nu_\tau$ candidate has been observed. The significance of the two
events in terms of a $\nu_\mu \to \nu_\tau$ oscillation signal is of 2.40
$\sigma$.


title:
Quantum walks of correlated photon pairs in two-dimensional waveguide
  arrays

abstract:
  We demonstrate quantum walks of correlated photons in a 2D network of
directly laser written waveguides coupled in a 'swiss cross' arrangement. The
correlated detection events show high-visibility quantum interference and
unique composite behaviour: strong correlation and independence of the quantum
walkers, between and within the planes of the cross. Violations of a
classically defined inequality, for photons injected in the same plane and in
orthogonal planes, reveal non-classical behaviour in a non-planar structure.


title:
Remarks on positive energy vacua via effective potentials in string
  theory

abstract:
  We study warped compactifications of string/M theory with the help of
effective potentials, continuing previous work of the last two authors and
Michael R. Douglas presented in arXiv:1206.1885. The dynamics of the conformal
factor of the internal metric, which is responsible for instabilities in these
constructions, is explored, and such instabilities are investigated in the
context of de Sitter vacua. We prove existence results for the equations of
motion in the case of a slowly varying warp factor, and the stability of such
solutions is also addressed. These solutions are a family of meta-stable de
Sitter vacua from type IIB string theory in a general non-supersymmetric setup.

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


title:
Mott-insulator to commensurate-solid transition in a 4He layer on
  \alpha-graphyne: Pseudo-spin symmetry breaking under a particle-induced
  pseudo-magnetic field

abstract:
  Path-integral Monte Carlo calculations were performed to study the adsorption
of $^4$He atoms on $\alpha$-graphyne. We find that one $^4$He atom can be
embedded onto the in-plane center of each hexagon of the graphyne. In the first
$^4$He layer above the $^4$He-embedded graphyne surface, a Mott insulating
state was observed at the areal density of 0.0706 \AA$^{-2}$ with three $^4$He
atoms occupying each hexagonal cell while the helium atoms form a commensurate
triangular solid at a density of 0.0941 \AA$^{-2}$. Here we show that the Ising
pseudo-spin symmetry introduced for two degenerate configurations of three
$^4$He atoms in a hexagonal cell can be broken by additional $^4$He atoms
placed at the hexagon vertices and the Mott-insulator to commensurate-solid
transition is a transition from a nonmagnetic spin liquid of frustrated
antiferromagnets to a spin-aligned ferromagnet under a particle-induced
pseudo-magnetic field.


title:
Disease universe: Visualisation of population-wide disease-wide
  associations

abstract:
  We apply a force-directed spring embedding graph layout approach to
electronic health records in order to visualise population-wide associations
between human disorders as presented in an individual biological organism. The
introduced visualisation is implemented on the basis of the Google maps
platform and can be found at http://disease-map.net . We argue that the
suggested method of visualisation can both validate already known specifics of
associations between disorders and identify novel never noticed association
patterns.


title: Cremmer--Gervais cluster structure on $SL_n$

abstract:
  We study natural cluster structures in the rings of regular functions on
simple complex Lie groups and Poisson-Lie structures compatible with these
cluster structures. According to our main conjecture, each class in the
Belavin-Drinfeld classification of Poisson-Lie structures on $\G$ corresponds
to a cluster structure in $\O(\G)$. We have shown before that this conjecture
holds for any $\G$ in the case of the standard Poisson--Lie structure and for
all Belavin-Drinfeld classes in $SL_n$, $n<5$. In this paper we establish it
for the Cremmer-Gervais Poisson-Lie structure on $SL_n$, which is the least
similar to the standard one. Besides, we prove that on $SL_3$ the cluster
algebra and the upper cluster algebra corresponding to the Cremmer-Gervais
cluster structure do not coincide, unlike the case of the standard cluster
structure. Finally, we show that the positive locus with respect to the
  Cremmer-Gervais cluster structure is contained in the set of totally positive
matrices.


title: A radical route to interstellar propylene formation

abstract:
  Complex organic molecules, such as propylene (CH3CHCH2), are detected in
molecular clouds (such as TMC1) with high fractional abundances (~2.10^{-9},
relative to hydrogen) that cannot be explained by gas-phase chemical reactions
under normal dark cloud conditions. To obtain such high abundances requires an
efficient grain-driven chemistry to be operating, coupled with effective
desorption of the complex organics back into the gas-phase. We propose that the
mechanism that we have previously described; rapid high density gas-phase
chemistry in the gas released following sudden, total, ice mantle sublimation -
can explain the high abundances, without recourse to ill-defined surface
chemical pathways. Our model provides a natural explanation for why it is that
some sources harbour high abundances of propylene, whilst others do not; based
on the age and level of dynamical activity within the source (which affects the
ice composition) and the chemical composition of the ambient gas.


title: Cluster categories for topologists

abstract:
  We consider triangulated orbit categories, with the motivating example of
cluster categories, in their usual context of algebraic triangulated
categories, then present them from another perspective in the framework of
topological triangulated categories.


title:
A Nash-Hormander iteration and boundary elements for the Molodensky
  problem

abstract:
  We investigate the numerical approximation of the nonlinear Molodensky
problem, which reconstructs the surface of the earth from the gravitational
potential and the gravity vector. The method, based on a smoothed
Nash-Hormander iteration, solves a sequence of exterior oblique Robin problems
and uses a regularization based on a higher-order heat equation to overcome the
loss of derivatives in the surface update. In particular, we obtain a
quantitative a priori estimate for the error after m steps, justify the use of
smoothing operators based on the heat equation, and comment on the accurate
evaluation of the Hessian of the gravitational potential on the surface, using
a representation in terms of a hypersingular integral. A boundary element
method is used to solve the exterior problem. Numerical results compare the
error between the approximation and the exact solution in a model problem.


title: Numerical simulations of the nonlinear Molodensky problem

abstract:
  We present a boundary element method to compute numerical approximations to
the non-linear Molodensky problem, which reconstructs the surface of the earth
from the gravitational potential and the gravity vector. Our solution procedure
solves a sequence of exterior oblique Robin problems and is based on a
Nash-H\"{o}rmander iteration. We apply smoothing with the heat equation to
overcome a loss of derivatives in the surface update. Numerical results compare
the error between the approximation and the exact solution in a model problem.


title:
Copper coated carbon fiber reinforced plastics for high and ultra high
  vacuum applications

abstract:
  We have used copper-coated carbon fiber reinforced plastic (CuCFRP) for the
construction of high and ultra-high vacuum recipients. The vacuum performance
is found to be comparable to typical stainless steel used for this purpose. In
test recipients we have reached pressures of 2E-8 mbar and measured a
desorption rate of 1E-11 mbar*liter/s/cm^2; no degradation over time (2 years)
has been found. Suitability for baking has been found to depend on the CFRP
production process, presumably on the temperature of the autoclave curing.
Together with other unique properties of CuCFRP such as low weight and being
nearly non-magnetic, this makes it an ideal material for many high-end vacuum
applications.


title: Constraining gravitational interactions in the M theory effective action

abstract:
  We consider purely gravitational interactions of the type D^{6n} R^4 in the
effective action of M theory which are related to the type IIA interactions of
the form e^{2n\phi_A} D^{6n} R^4 where \phi_A is the type IIA dilaton. The
coefficients of the M theory interactions are determined by the strongly
coupled type IIA theory. Given the nature of the dilaton dependence, it is
plausible that for low values of n, the coefficient has a similar structure as
the genus (n+1) string amplitude of the type IIA D^{6n} R^4 interaction, namely
the transcendental nature. Assuming this, and focussing on the even--even spin
structure part of the type IIA string amplitude, this coefficient is given by
the type IIB genus (n+1) amplitude, which we constrain using supersymmetry,
S--duality and maximal supergravity. The source terms of the Poisson equations
satisfied by the S--duality invariant IIB couplings play a central role in the
analysis. This procedure yields partial contributions to several multi--loop
type IIB string amplitudes, from which we extract the transcendental nature of
the corresponding M theory couplings. For n \leq 2, all possible source terms
involve only BPS couplings. While the R^4 and D^6 R^4 M theory couplings agree
with known results, the coefficient of the D^{12} R^4 interaction takes the
form \zeta (2)^3 (\Omega_1+\Omega_2 \zeta (3)). We also analyze the D^{18} R^4
and D^{24} R^4 interactions, and show that their coefficients have at least the
terms \zeta (2)^4 (\tilde\Omega_1 +\tilde\Omega_2\zeta (3) +\tilde\Omega_3\zeta
(5)) and \zeta (2)^5 (\underline\Omega_1 +\underline\Omega_2\zeta (3)
+\underline\Omega_3\zeta (5) + \underline\Omega_4\zeta (3)^2 +
\underline\Omega_5\zeta (7) +\underline\Omega_6\zeta (3) \zeta (5)
+\underline\Omega_7 \zeta (3)^3) respectively. The various undetermined
constants have vanishing transcendentality.


title: A place-focused model for social networks in cities

abstract:
  The focused organization theory of social ties proposes that the structure of
human social networks can be arranged around extra-network foci, which can
include shared physical spaces such as homes, workplaces, restaurants, and so
on. Until now, this has been difficult to investigate on a large scale, but the
huge volume of data available from online location-based social services now
makes it possible to examine the friendships and mobility of many thousands of
people, and to investigate the relationship between meetings at places and the
structure of the social network. In this paper, we analyze a large dataset from
Foursquare, the most popular online location-based social network. We examine
the properties of city-based social networks, finding that they have common
structural properties, and that the category of place where two people meet has
very strong influence on the likelihood of their being friends. Inspired by
these observations in combination with the focused organization theory, we then
present a model to generate city-level social networks, and show that it
produces networks with the structural properties seen in empirical data.


title: Superconducting Graphene: the conspiracy of doping and strain

abstract:
  Graphene has exhibited a wealth of fascinating properties, but is also known
not to be a superconductor. Remarkably, we show that graphene can be made a
conventional Bardeen-Cooper-Schrieffer superconductor by the combined effect of
charge doping and tensile strain. While the effect of doping is obvious to
enlarge Fermi surface, the effect of strain is profound to greatly increase the
electron-phonon coupling. At the experimental accessible doping (4E+14cm-2) and
strain (~16%) levels, the superconducting critical temperature Tc reaches as
high as ~30 K, the highest for a single-element material above the liquid
hydrogen temperature. This significantly makes graphene a commercially viable
superconductor.


title: Rational surface maps with invariant meromorphic two forms

abstract:
  We consider a rational map f:S->S of a complex projective surface together
with an invariant meromorphic two form. Under a mild topological assumption on
the map, we show that the zeroes of the invariant form can be eliminated by
birational change of coordinate. In this context, when the form has no zeroes,
we investigate the notion of algebraic stability for f. We show in particular
that algebraic stability is equivalent to a more tractable condition involving
the behavior of f on the poles of the form. Finally, we illustrate our results
in the particular case where S is the projective plane and the invariant form
is dx dy / xy, showing that our criterion for stability translates to whether
or not the rotation number for a certain circle homeomorphism is rational.


title:
Calculation of AC losses in stacks and coils made of second generation
  high temperature superconducting tapes for large scale applications

abstract:
  A homogenization method to model a stack of second generation (2G) High
Temperature Superconducting (HTS) tapes under AC applied transport current or
magnetic field has been obtained. The idea is to find an anisotropic bulk
equivalent for the stack, such that the geometrical layout of the internal
alternating structures of insulating, metallic, superconducting and substrate
layers is "washed" out while keeping the overall electromagnetic behavior of
the original stack. We disregard assumptions upon the shape of the critical
region and use a power law E-J relationship allowing for overcritical current
densities to be considered. The method presented here allows for a
computational speedup factor of up to 2 orders of magnitude when compared to
full 2-D simulations taking into account the actual dimensions of the stacks
without compromising accuracy.


title: Fractals of graphene quantum dots in photoluminescence of shungite

abstract:
  Photoluminescence of graphene quantum dots (GQDs) of shungite, attributed to
individual fragments of reduced graphene oxide (rGO), has been studied for the
frozen rGO colloidal dispersions in water, carbon tetrachloride, and toluene.
Morphological study shows a steady trend of GQDs to form fractals and a drastic
change in the colloids fractal structure caused by solvent was reliably
established. Spectral study reveals a dual character of emitting centers:
individual GQDs are responsible for the spectra position while fractal
structure of GQD colloids provides high broadening of the spectra due to
structural inhomogeneity of the colloidal dispersions and a peculiar dependence
on excitation wavelength. For the first time, photoluminescence spectra of
individual GQDs were observed in frozen toluene dispersions which pave the way
for a theoretical treatment of GQD photonics.


title: A simple minded question: Do we live in the four-dimensional spacetime?

abstract:
  A new approach in the Newtonian space and time, based upon the assumption
that inertial mass is the quantitative measure of the matter. It has been shown
that in case of a special physical system, a supposed matter transfer may
reproduce the relativistic mass increase of an accelerated particle. As a
consequence, the relativistic time dilation in the accelerated system can be
explained. It is shown that subsequent accelerations produce systems, whose
equivalent masses and the rate of the equivalent clocks do not depend on their
relative velocity in a way predicted by the theory of special relativity. It is
also shown that adding a small velocity dependent component to the static
gravitational force, the measured peri-helium shift and the light deflection
can be reproduced. Some explanations of the experienced behaviour of the
photons, based on their changing mass, are offered.


title: GL(n) equivariant Minkowski valuations

abstract:
  A classification of all continuous GL(n) equivariant Minkowski valuations on
convex bodies in $\mathbb{R}^n$ is established. Together with recent results of
F.E. Schuster and the author, this article therefore completes the description
of all continuous GL(n) intertwining Minkowski valuations.


title: Achieving Speedup in Aggregate Risk Analysis using Multiple GPUs

abstract:
  Stochastic simulation techniques employed for the analysis of portfolios of
insurance/reinsurance risk, often referred to as `Aggregate Risk Analysis', can
benefit from exploiting state-of-the-art high-performance computing platforms.
In this paper, parallel methods to speed-up aggregate risk analysis for
supporting real-time pricing are explored. An algorithm for analysing aggregate
risk is proposed and implemented for multi-core CPUs and for many-core GPUs.
Experimental studies indicate that GPUs offer a feasible alternative solution
over traditional high-performance computing systems. A simulation of 1,000,000
trials with 1,000 catastrophic events per trial on a typical exposure set and
contract structure is performed in less than 5 seconds on a multiple GPU
platform. The key result is that the multiple GPU implementation can be used in
real-time pricing scenarios as it is approximately 77x times faster than the
sequential counterpart implemented on a CPU.


title:
Fermi-LAT upper limits on gamma-ray emission from colliding wind
  binaries

abstract:
  Context: Colliding wind binaries (CWBs) are thought to give rise to a
plethora of physical processes including acceleration and interaction of
relativistic particles. Observation of synchrotron radiation in the radio band
confirms there is a relativistic electron population in CWBs. Accordingly, CWBs
have been suspected sources of high-energy gamma-ray emission since the COS-B
era. Theoretical models exist that characterize the underlying physical
processes leading to particle acceleration and quantitatively predict the
non-thermal energy emission observable at Earth. Aims: We strive to find
evidence of gamma-ray emission from a sample of seven CWB systems: WR 11, WR
70, WR 125, WR 137, WR 140, WR 146, and WR 147. Theoretical modelling
identified these systems as the most favourable candidates for emitting
gamma-rays. We make a comparison with existing gamma-ray flux predictions and
investigate possible constraints. Methods: We used 24 months of data from the
Large Area Telescope (LAT) on-board the Fermi Gamma Ray Space Telescope to
perform a dedicated likelihood analysis of CWBs in the LAT energy range.
Results: We find no evidence of gamma-ray emission from any of the studied CWB
systems and determine corresponding flux upper limits. For some CWBs the
interplay of orbital and stellar parameters renders the Fermi-LAT data not
sensitive enough to constrain the parameter space of the emission models. In
the cases of WR140 and WR147, the Fermi-LAT upper limits appear to rule out
some model predictions entirely and constrain theoretical models over a
significant parameter space. A comparison of our findings to the CWB eta Car is
made.


title:
Line-of-Sight Obstruction Analysis for Vehicle-to-Vehicle Network
  Simulations in a Two-Lane Highway Scenario

abstract:
  In vehicular ad-hoc networks (VANETs) the impact of vehicles as obstacles has
largely been neglected in the past. Recent studies have reported that the
vehicles that obstruct the line-of-sight (LOS) path may introduce 10-20 dB
additional loss, and as a result reduce the communication range. Most of the
traffic mobility models (TMMs) today do not treat other vehicles as obstacles
and thus can not model the impact of LOS obstruction in VANET simulations. In
this paper the LOS obstruction caused by other vehicles is studied in a highway
scenario. First a car-following model is used to characterize the motion of the
vehicles driving in the same direction on a two-lane highway. Vehicles are
allowed to change lanes when necessary. The position of each vehicle is updated
by using the car-following rules together with the lane-changing rules for the
forward motion. Based on the simulated traffic a simple TMM is proposed for
VANET simulations, which is capable to identify the vehicles that are in the
shadow region of other vehicles. The presented traffic mobility model together
with the shadow fading path loss model can take in to account the impact of LOS
obstruction on the total received power in the multiple-lane highway scenarios.


title: MesonNet 2013 International Workshop. Mini-proceedings

abstract:
  The mini-proceedings of the MesonNet 2013 International Workshop held in
Prague from June 17th to 19th, 2013, are presented. MesonNet is a research
network within EU HadronPhysics3 project (1/2012 -- 12/2014). The web page of
the conference, which contains all talks, can be found at
http://ipnp.mff.cuni.cz/mesonnet13


title:
Evolutionary Extortion and Mischief: Zero Determinant strategies in
  iterated 2x2 games

abstract:
  This paper studies the mechanisms, implications, and potential applications
of the recently discovered class of Zero Determinant (ZD) strategies in
iterated 2x2 games. These strategies were reported to successfully extort pure
economic maximizers, and to mischievously determine the set of feasible
long-term payoffs in iterated Prisoners' Dilemma by enforcing linear
constraints on both players' expected average scores.
  These results are generalized for all symmetric 2x2 games and a general
Battle of the Sexes, exemplified by four common games. Additionally, a
comparison to conventional strategies is made and typical ZD gameplay
simulations are analyzed along with convergence speeds. Several response
strategies are discussed, including a glance on how time preferences change
previous results. Furthermore, a possibility of retaliation is presented: when
maximin scores exceed the minimum symmetric payoff, it is possible to extort
the extortioner.
  Finally, a summary of findings from evolutionary game theory shows that
mischief is limited by its own malice. Nevertheless, this does not challenge
the result that mindless economic maximization is subject to extortion: the
study of ZD strategies reveals exciting new perspectives and opportunities in
game theory, both evolutionary and classic.