title:
Radiatively Inefficient Accretion Flow Simulations with Cooling:
  Implications for Black Hole Transients

abstract:
  We study the effects of optically thin radiative cooling on the structure of
radiatively inefficient accretion flows (RIAFs). The flow structure is
geometrically thick, and independent of the gas density and cooling, if the
cooling time is longer than the viscous timescale (i.e., $t_{\rm cool} \gtrsim
t_{\rm visc}$). For higher densities, the gas can cool before it can accrete
and forms the standard geometrically thin, optically thick Shakura-Sunyaev
disk. For usual cooling processes (such as bremsstrahlung), we expect an inner
hot flow and an outer thin disk. For a short cooling time the accretion flow
separates into two phases: a radiatively inefficient hot coronal phase and a
cold thin disk. We argue that there is an upper limit on the density of the hot
corona corresponding to a critical value of $t_{\rm cool}/t_{\rm ff} (\sim
10-100)$, the ratio of the cooling time and the free-fall time. Based on our
simulations, we have developed a model for transients observed in black hole
X-ray binaries (XRBs). An XRB in a quiescent hot RIAF state can transition to a
cold black-body dominated state because of an increase in the mass accretion
rate. The transition from a thin disk to a RIAF happens because of mass
exhaustion due to accretion; the transition happens when the cooling time
becomes longer than the viscous time at inner radii. Since the viscous
timescale for a geometrically thin disk is quite long, the high-soft state is
expected to be long-lived. The different timescales in black hole transients
correspond to different physical processes such as viscous evolution, cooling,
and free-fall. Our model captures the overall features of observed state
transitions in XRBs.


title:
A likelihood ratio test for monotone baseline hazard functions in the
  Cox model

abstract:
  We consider a likelihood ratio method for testing whether a monotone baseline
hazard function in the Cox model has a particular value at a fixed point. The
characterization of the estimators involved is provided both in the
nondecreasing and the nonincreasing setting. These characterizations facilitate
the derivation of the asymptotic distribution of the likelihood ratio test,
which is identical in the nondecreasing and in the nonincreasing case. The
asymptotic distribution of the likelihood ratio test enables, via inversion,
the construction of pointwise confidence intervals. Simulations show that these
confidence intervals exhibit comparable coverage probabilities with the
confidence intervals based on the asymptotic distribution of the nonparametric
maximum likelihood estimator of a monotone baseline hazard function.


title: Happiness and the Patterns of Life: A Study of Geolocated Tweets

abstract:
  The patterns of life exhibited by large populations have been described and
modeled both as a basic science exercise and for a range of applied goals such
as reducing automotive congestion, improving disaster response, and even
predicting the location of individuals. However, these studies previously had
limited access to conversation content, rendering changes in expression as a
function of movement invisible. In addition, they typically use the
communication between a mobile phone and its nearest antenna tower to infer
position, limiting the spatial resolution of the data to the geographical
region serviced by each cellphone tower. We use a collection of 37 million
geolocated tweets to characterize the movement patterns of 180,000 individuals,
taking advantage of several orders of magnitude of increased spatial accuracy
relative to previous work. Employing the recently developed sentiment analysis
instrument known as the 'hedonometer', we characterize changes in word usage as
a function of movement, and find that expressed happiness increases
logarithmically with distance from an individual's average location.


title:
Automated measurements of diffuse interstellar bands in early-type star
  spectra Correlations with the Color Excess

abstract:
  Stellar spectroscopic surveys may bring useful statistical information on the
links between Diffuse Interstellar Bands (DIBs) and interstellar environment.
DIB databases can also be used as a complementary tool for locating
interstellar (IS) clouds. Our goal is to develop fully automated methods of DIB
measurements to be applied to extensive data from stellar surveys. We present a
method appropriate for early-type nearby stars, its application to
high-resolution spectra of 130 targets recorded with ESO FEROS spectrograph,
and comparisons with other determinations. Using a DIB average profile deduced
from the most reddened stars, we performed an automated fitting of a
combination of a smooth stellar continuum, the DIB profile, and, when
necessary, a synthetic telluric transmission. Measurements are presented for 16
DIBs in the optical domain that could be extracted automatically: 4726.8,
4762.6, 4963.9, 5780.4, 5797.1, 5849.8, 6089.8, 6196.0, 6203.0-6204.5, 6269.8,
6283.8, 6379.3, 6445.3, 6613.6, 6660.7, and 6699.3 {\AA}.


title:
Learning from Nature to Improve the Heat Generation of Iron-Oxide
  Nanoparticles for Magnetic Hyperthermia Applications

abstract:
  The performance of magnetic nanoparticles is intimately entwined with their
structure, mean size and magnetic anisotropy. Besides, ensembles offer a unique
way of engineering the magnetic response by modifying the strength of the
dipolar interactions between particles. Here we report on an experimental and
theoretical analysis of magnetic hyperthermia, a rapidly developing technique
in medical research and oncology. Experimentally, we demonstrate that
single-domain cubic iron oxide particles resembling bacterial magnetosomes have
superior magnetic heating efficiency compared to spherical particles of similar
sizes. Monte Carlo simulations at the atomic level corroborate the larger
anisotropy of the cubic particles in comparison with the spherical ones, thus
evidencing the beneficial role of surface anisotropy in the improved heating
power. Moreover we establish a quantitative link between the particle
assembling, the interactions and the heating properties. This knowledge opens
new perspectives for improved hyperthermia, an alternative to conventional
cancer therapies.


title: Stein fillable contact 3-manifolds and positive open books of genus one

abstract:
  A two-dimensional open book (S,h) determines a closed, oriented
three-manifold Y(S,h) and a contact structure C(S,h) on Y(S,h). The contact
structure C(S,h) is Stein fillable if h is positive, i.e. h can be written as a
product of right-handed Dehn twists. Work of Wendl implies that when S has
genus zero the converse statement holds, that is if C(S,h) is Stein fillable
then h is positive. On the other hand, results by Wand and by Baker, Etnyre and
Van Horn-Morris imply the existence of counterexamples to the converse
statement with S of arbitrary genus strictly greater than one. The main purpose
of this paper is to prove the converse statement under the assumption that S is
a one-holed torus and Y(S,h) is a Heegaard Floer L-space.


title:
Fast-Ion Deuterium Alpha spectroscopic observations of the effects of
  fishbones in the Mega-Ampere Spherical Tokamak

abstract:
  Using the recently-installed Fast-Ion Deuterium Alpha (FIDA) spectrometer,
the effects of low-frequency (20-50 kHz) chirping energetic particle modes with
toroidal mode number n \geq 1 on the fast-ion population in MAST plasmas are
considered. Results from the FIDA diagnostic are presented and discussed in the
light of the present theoretical understanding of these modes, known as
fishbones, in plasmas with reversed shear. Measurements of the fast-ion
population reveal strong redistribution of fast ions in both real and velocity
space as a result of the fishbones. Time-resolved measurements throughout the
evolution of a fishbone show radial redistribution of fast ions with energies
up to 95% of the primary beam injection energy. Correlations between changes in
the FIDA signal and the peak time derivative of the magnetic field perturbation
are observed in a limited range of operating scenarios. The transient reduction
in signal caused by a fishbone may in some cases reach 50% of the signal
intensity before mode onset.


title: Interpreting Z(3900)

abstract:
  A new charged state, called $Z_c(3900)$ has been recently observed by BESIII
collaboration in $J/\psi\pi^{\pm}$ channel. The same has been confirmed by
Belle (called Z(3894.5 in the Belle paper). In this short note we discuss
probable interpretations of this charmonium like state which we call Z(3900).


title:
Charge doping versus disorder in CeFeAsO: do the in- and out-of-plane
  dilutions play the same role?

abstract:
  We provide direct experimental evidence for the identical effect of the
in-plane Fe$_{1-x}$Co$_{x}$ and of the out-of-plane O$_{1-x}$F$_{x}$ chemical
dilutions on the itinerant spin-density-wave (SDW) magnetic phase in CeFeAsO.
Remarkably, the suppression of SDW is not sensitive at all to the different
kinds of disorder introduced in the two cases. Still, it is clearly shown that
the sizeable in-plane disorder induced by the Fe$_{1-x}$Co$_{x}$ substitution
is highly effective in suppressing $T_{\textrm{c}}$. Differently from what is
observed in CeFeAsO$_{1-x}$F$_{x}$, the ordered magnetic phase of the Ce
sublattice is preserved throughout the whole phase diagram in
CeFe$_{1-x}$Co$_{x}$AsO ($x \leq 0.2$). An intriguing effect is encountered,
whereby the magnetic coupling among Ce$^{3+}$ ions is enhanced by the
superconducting phase.


title:
Heavy quarkonium production through the top quark decays via flavor
  changing neutral currents

abstract:
  Properties of the production channel have been recalculated and discussed in
detail in arXiv:1808.01231.


title:
Non-contact method for measurement of the microwave conductivity of
  graphene

abstract:
  We report a non-contact method for conductivity and sheet resistance
measurements of graphene samples using a high Q microwave dielectric resonator
perturbation technique, with the aim of fast and accurate measurement of
microwave conductivity and sheet resistance of monolayer and few layers
graphene samples. The dynamic range of the microwave conductivity measurements
makes this technique sensitive to a wide variety of imperfections and
impurities and can provide a rapid non-contacting characterisation method.
Typically the graphene samples are supported on a low-loss dielectric
substrate, such as quartz, sapphire or SiC. This substrate is suspended in the
near-field region of a small high Q sapphire puck microwave resonator. The
presence of the graphene perturbs both centre frequency and Q value of the
microwave resonator. The measured data may be interpreted in terms of the real
and imaginary components of the permittivity, and by calculation, the
conductivity and sheet resistance of the graphene. The method has great
sensitivity and dynamic range. Results are reported for graphene samples grown
by three different methods: reduced graphene oxide (GO), chemical vapour
deposition (CVD) and graphene grown epitaxially on SiC. The latter method
produces much higher conductivity values than the others.


title: The mystery of T Pyx; the 2011 explosion

abstract:
  T Pyx is a recurrent nova which has undergone eruptions on an almost regular
basis every 20 years until reaching a long lasting quiescence between 1967 and
2011. We observed the long awaited 2011 explosion in the optical and near
infrared with intermediate spectral resolution. In this paper we report on the
change in the spectral type of the nova (both during its rise and during its
fading), as well as the observed changes in the expansion velocities. We also
present an interpretation of these changes and set them in the general
framework of a new understanding of nova classification.


title: The upgrade of the ALICE Inner Tracking System

abstract:
  ALICE is a general purpose experiment dedicated to the study of
nucleus-nucleus collisions at LHC. After more than 3 years of successful
operation, an upgrade of the apparatus during the second long shutdown of LHC
(LS2) in 2017/18 is in preparation. One of the major goals of the proposed
upgrade is to extend the physics reach for rare probes at low transverse
momentum. The reconstruction of the rare probes requires a precise
determination of the primary and secondary vertices that is performed in ALICE
by the Inner Tracking System (ITS). The present ITS made of 6 layers of three
technologies of silicon devices allows, for example, to reconstruct D mesons
with the transverse momentum down to ~2 GeV/c.
  Further extension of this range towards lower pT requires the installation of
the new ITS consisting of 7 layers of silicon detectors with significantly
better single point resolution and reduced material budget. It is expected that
the new system will allow to improve the impact parameter resolution by a
factor of ~3. Moreover, the data rate capability of the upgraded ITS should be
significantly improved in order to exploit the full expected LHC lead-lead
interaction rate of 50 kHz, almost two orders of magnitude above the present
readout rate.
  The present contribution describes first the ITS upgrade requirements
followed by the conceptual design of the new system and its expected
performance. Secondly, an overview of the different R&D activities from the
concept towards the final detector is given.


title: On the structure of the class NP

abstract:
  A new class UF of problems is introduced, strictly included in the class NP,
which arises in the analysis of the time verifying the intermediate results of
computations. The implications of the introduction of this class are
considered. First of all, we prove that $P\not= NP$ and establish that it needs
to consider the problem "P vs UF" instead the problem "P vs NP". Also, we
determine the set-theoretical of properties of a one-way functions that used in
cryptology.


title:
Numerical calculation of magnetic form factors of complex shape
  nano-particles coupled with micromagnetic simulations

abstract:
  We investigate the calculation of the magnetic form factors of nano-objects
with complex geometrical shapes and non homogeneous magnetization
distributions. We describe a numerical procedure which allows to calculate the
3D magnetic form factor of nano-objects from realistic magnetization
distributions obtained by micromagnetic calculations. This is illustrated in
the canonical cases of spheres, rods and platelets. This work is a first step
towards a 3D vectorial reconstruction of the magnetization at the nanometric
scale using neutron scattering techniques.


title: Interaction Nets in Russian

abstract:
  Draft translation to Russian of Chapter 7, Interaction-Based Models of
Computation, from Models of Computation: An Introduction to Computability
Theory by Maribel Fernandez. "In this chapter, we study interaction nets, a
model of computation that can be seen as a representative of a class of models
based on the notion of 'computation as interaction'. Interaction nets are a
graphical model of computation devised by Yves Lafont in 1990 as a
generalisation of the proof structures of linear logic. It can be seen as an
abstract formalism, used to define algorithms and analyse their cost, or as a
low-level language into which other programming languages can be compiled. This
is fruitful because interaction nets can be implemented with reasonable
efficiency."


title:
Large-area [Fe II] Line Mapping of the Supernova Remnant IC443 with the
  IRSF/SIRIUS

abstract:
  We present the result of near-infrared (near-IR) [Fe II] line mapping of the
supernova remnant IC443 with the IRSF/SIRIUS, using the two narrow-band filters
tuned for the [Fe II] 1.257 micron and [Fe II] 1.644 micron lines. Covering a
large area of 30' x 35', our observations reveal that [Fe II] filamentary
structures exist all over the remnant, not only in an ionic shock shell, but
also in a molecular shock shell and a central region inside the shells. With
the two [Fe II] lines, we performed corrections for dust extinction to derive
the intrinsic line intensities. We also obtained the intensities of thermal
emission from the warm dust associated with IC443, using the far- and mid-IR
images taken with AKARI and Spitzer, respectively. As a result, we find that
the [Fe II] line emission relative to the dust emission notably enhances in the
inner central region. We discuss causes of the enhanced [Fe II] line emission,
estimating the Fe+ and dust masses.


title:
Time-dependent galactic winds I. Structure and evolution of galactic
  outflows accompanied by cosmic ray acceleration

abstract:
  Cosmic rays are transported out of the galaxy by diffusion and advection due
to streaming along magnetic field lines and resonant scattering off
self-excited MHD waves. Thus momentum is transferred to the plasma via the
frozen-in waves as a mediator assisting the thermal pressure in driving a
galactic wind. The bulk of the Galactic CRs are accelerated by shock waves
generated in SNRs, a significant fraction of which occur in OB associations on
a timescale of several $10^7$ years. We examine the effect of changing boundary
conditions at the base of the galactic wind due to sequential SN explosions on
the outflow. Thus pressure waves will steepen into shock waves leading to in
situ post-acceleration of GCRs. We performed simulations of galactic winds in
flux tube geometry appropriate for disk galaxies, describing the CR
diffusive-advective transport in a hydrodynamical fashion along with the energy
exchange with self-generated MHD waves. Our time-dependent CR hydrodynamic
simulations confirm the existence of time asymptotic outflow solutions (for
constant boundary conditions). It is also found that high-energy particles
escaping from the Galaxy and having a power-law distribution in energy
($\propto E^{-2.7}$) similar to the Milky Way with an upper energy cut-off at
$\sim 10^{15}$ eV are subjected to efficient and rapid post-SNR acceleration in
the lower galactic halo up to energies of $10^{17} - 10^{18}$ eV by multiple
shock waves propagating through the halo. The particles can gain energy within
less than $3\,$kpc from the galactic plane corresponding to flow times less
than $5\cdot 10^6\,$years. The mechanism described here offers a natural
solution to explain the power-law distribution of CRs between the "knee" and
the "ankle". The mechanism described here offers a natural and elegant solution
to explain the power-law distribution of CRs between the "knee" and the
"ankle".


title:
On nonlinear potential theory, and regular boundary points, for the
  p-Laplacian in N space variables

abstract:
  We turn back to some pioneering results concerning, in particular, nonlinear
potential theory and non-homogeneous boundary value problems for the so called
p-Laplacian operator. Unfortunately these results, obtained at the very
beginning of the seventies, were kept in the shade. We believe that our proofs
are still of interest, in particular due to their extreme simplicity. Moreover,
some contributions seem to improve the results quoted in the current
literature.


title: Projections in duals to Asplund spaces made without Simons' lemma

abstract:
  G. Godefroy and the second author of this note proved in 1988 that in duals
to Asplund spaces there always exists a projectional resolution of the
identity. A few years later, Ch. Stegall succeeded to drop from the original
proof a deep lemma of S. Simons. Here, we rewrite the condensed argument of Ch.
Stegall in a more transparent and detailed way. We actually show that this
technology of Ch. Stegall leads to a bit stronger/richer object ---the so
called projectional skeleton--- recently constructed by W. Kubi\'s, via S.
Simons' lemma and with help of elementary submodels from logic.


title:
Electronic excitation energies of molecular systems from the
  Bethe-Salpeter equation: Example of the H2 molecule

abstract:
  We review the Bethe-Salpeter equation (BSE) approach to the calculation of
electronic excitation energies of molecular systems. We recall the general
Green's function many-theory formalism and give the working equations of the
BSE approach within the static GW approximation with and without spin
adaptation in an orbital basis. We apply the method to the pedagogical example
of the H2 molecule in a minimal basis, testing the effects of the choice of the
starting one-particle Green's function. Using the non-interacting one-particle
Green's function leads to incorrect energy curves for the first singlet and
triplet excited states in the dissociation limit. Starting from the exact
one-particle Green's function leads to a qualitatively correct energy curve for
the first singlet excited state, but still an incorrect energy curve for the
triplet excited state. Using the exact one-particle Green's function in the BSE
approach within the static GW approximation also leads to a number of
additional excitations, all of them being spurious except for one which can be
identified as a double excitation corresponding to the second singlet excited
state.


title:
The Largest Laplacian and Signless Laplacian H-Eigenvalues of a Uniform
  Hypergraph

abstract:
  In this paper, we show that the largest Laplacian H-eigenvalue of a
$k$-uniform nontrivial hypergraph is strictly larger than the maximum degree
when $k$ is even. A tight lower bound for this eigenvalue is given. For a
connected even-uniform hypergraph, this lower bound is achieved if and only if
it is a hyperstar. However, when $k$ is odd, it happens that the largest
Laplacian H-eigenvalue is equal to the maximum degree, which is a tight lower
bound. On the other hand, tight upper and lower bounds for the largest signless
Laplacian H-eigenvalue of a $k$-uniform connected hypergraph are given. For a
connected $k$-uniform hypergraph, the upper (respectively lower) bound of the
largest signless Laplacian H-eigenvalue is achieved if and only if it is a
complete hypergraph (respectively a hyperstar). The largest Laplacian
H-eigenvalue is always less than or equal to the largest signless Laplacian
H-eigenvalue. When the hypergraph is connected, the equality holds here if and
only if $k$ is even and the hypergraph is odd-bipartite.


title: Continuous THz emission from dipolaritons

abstract:
  We propose a scheme of continuous tunable THz emission based on dipolaritons
--- mixtures of strongly interacting cavity photons and direct excitons, where
the latter are coupled to indirect excitons via tunnelling. We investigate the
property of multistability under continuous wave (CW) pumping, and the
stability of the solutions. We establish the conditions of parametric
instability, giving rise to oscillations in density between the direct exciton
and indirect modes under CW pumping. In this way we achieve continuous and
tunable emission in the THz range in a compact single-crystal device. We show
that the emission frequency can be tuned in a certain range by varying an
applied electric field and pumping conditions. Finally, we demonstrate the
dynamic switching between different phases in our system, allowing rapid
control of THz radiation.


title: Rough Potential Recovery in the Plane

abstract:
  We reconstruct compactly supported potentials with only half a derivative in
$L^2$ from the scattering amplitude at a fixed energy. For this we draw a
connection between the recently introduced method of Bukhgeim, which uniquely
determined the potential from the Dirichlet-to-Neumann map, and a question of
Carleson regarding the convergence to initial data of solutions to
time-dependent Schr\"odinger equations. We also provide examples of compactly
supported potentials, with $s$ derivatives in $L^2$ for any $s<1/2$, which
cannot be recovered by these means. Thus the recovery method has a different
threshold in terms of regularity than the corresponding uniqueness result.


title: RFID Authentication Against an Unsecure Backend Server

abstract:
  This paper address a new problem in RFID authentication research for the
first time. That is, existing RFID authentication schemes generally assume that
the backend server is absolutely secure, however, this assumption is rarely
tenable in practical conditions. It disables existing RFID authentication
protocols from being safely applied to a reallife scenario in which the backend
server is actually vulnerable, compromised or even malicious itself. We propose
an RFID authentication scheme against an unsecure backend server. It is based
on hash chain, searching over encrypted data, and coprivacy, defending against
the privacy revealing to the backend server. The proposed scheme is scalable,
resistant to desynchronization attacks, and provides mutual authentication in
only three frontend communication steps. Moreover, it is the first scheme
meeting the special security and privacy requirement for a cloud-based RFID
authentication scenario in which the backend server is untrustworthy to readers
held by cloud clients.


title:
Backward Stochastic Differential Equations Associated with the Vorticity
  Equations

abstract:
  We derive a non-linear version of the Feynman-Kac formula for the solutions
of the vorticity equation in dimension 2 with space periodic boundary
conditions. We prove the existence (global in time) and uniqueness for a
stochastic terminal value problem associated with the vorticity equation in
dimension 2.


title: Single pion production in neutrino nucleus scattering

abstract:
  We study one pion production in both charged and neutral current neutrino
nucleus scattering for neutrino energies below 2 GeV. We use a theoretical
model for one pion production at the nucleon level that we correct for medium
effects. The results are incorporated into a cascade program that apart from
production also includes the pion final state interaction inside the nucleus.
Besides, in some specific channels coherent pion production is also possible
and we evaluate its contribution as well. Our results for total and
differential cross sections are compared with recent data from the MiniBooNE
Collaboration. The model provides an overall acceptable description of data,
better for NC than for CC channels, although theory is systematically below
data. Differential cross sections, folded with the full neutrino flux, show
that most of the missing pions lie on the forward direction and at high
energies.


title: The air shower maximum probed by Cherenkov effects from radio emission

abstract:
  Radio detection of cosmic-ray-induced air showers has come to a flight the
last decade. Along with the experimental efforts, several theoretical models
were developed. The main radio-emission mechanisms are established to be the
geomagnetic emission due to deflection of electrons and positrons in Earth's
magnetic field and the charge-excess emission due to a net electron excess in
the air shower front. It was only recently shown that Cherenkov effects play an
important role in the radio emission from air showers. In this article we show
the importance of these effects to extract quantitatively the position of the
shower maximum from the radio signal, which is a sensitive measure for the mass
of the initial cosmic ray. We also show that the relative magnitude of the
charge-excess and geomagnetic emission changes considerably at small observer
distances where Cherenkov effects apply.


title:
Electronic excitations from a linear-response range-separated hybrid
  scheme

abstract:
  We study linear-response time-dependent density-functional theory (DFT) based
on the single-determinant range-separated hybrid (RSH) scheme, i.e. combining a
long-range Hartree-Fock exchange kernel with a short-range DFT
exchange-correlation kernel, for calculating electronic excitation energies of
molecular systems. It is an alternative to the long-range correction (LC)
scheme which has a standard full-range DFT correlation kernel instead of only a
short-range one. We discuss the local-density approximation (LDA) to the
short-range exchange-correlation kernel, and assess the performance of the
linear-response RSH scheme for singlet-singlet and singlet-triplet valence and
Rydberg excitations in the N2, CO, H2CO, C2H4, and C6H6 molecules, and for the
first charge-transfer excitation in the C2H4-C2F4 dimer. The introduction of
long-range HF exchange corrects the underestimation of charge-transfer and
high-lying Rydberg excitation energies obtained with standard (semi)local
density-functional approximations, but also leads to underestimated excitation
energies to low-lying spin-triplet valence states which can be cured by the
Tamm-Dancoff approximation. This work thus suggests that the present
linear-response RSH scheme is a reasonable starting approximation for
describing electronic excitation energies, even before adding an explicit
treatment of long-range correlation.


title: Bulk-edge correspondence in fractional Chern insulators

abstract:
  It has been recently realized that strong interactions in topological Bloch
bands give rise to the appearance of novel states of matter. Here we study
connections between these systems -- fractional Chern insulators and the
fractional quantum Hall states -- via generalization of a gauge-fixed
Wannier-Qi construction in the cylinder geometry. Our setup offers a number of
important advantages compared to the earlier exact diagonalization studies on a
torus. Most notably, it gives access to edge states and to a single-cut orbital
entanglement spectrum, hence to the physics of bulk-edge correspondence. It is
also readily implemented in the state-of-the-art density matrix renormalisation
group method that allows for numerical simulations of significantly larger
systems. We demonstrate our general approach on examples of flat-band models on
ruby and kagome lattices at bosonic filling fractions $\nu=1/2$ and $\nu=1$,
which show the signatures of (non)-Abelian phases, and establish the
correspondence between the physics of edge states and the entanglement in the
bulk. Notably, we find that the non-Abelian $\nu=1$ phase can be stabilized by
purely on-site interactions in the presence of a confining potential.


title: On Conic Fourier Multipliers

abstract:
  We prove a weighted inequality which controls conic Fourier multiplier
operators in terms of lacunary directional maximal operators. By bounding the
maximal operators, this enables us to conclude that the multiplier operators
are bounded on $L^p(\mathbb{R}^3)$ with $1<p<\infty$.


title: Pais-Uhlenbeck Oscillator with a Benign Friction Force

abstract:
  It is shown that the Pais-Uhlenbeck oscillator with damping, considered by
Nesterenko, is a special case of a more general oscillator that has not only a
first order, but also a third order friction term. If the corresponding damping
constants, \alpha\ and \beta, are both positive and below certain critical
values, then the system is stable. In particular, if \alpha = - \beta, then we
have the unstable Nesterenko's oscillator


title: Process optimized quantum cloners via semidefinite programming

abstract:
  We apply semidefinite programming for designing 1 to 2 symmetric qubit
quantum cloners. These are optimized for the average fidelity of their joint
output state with respect to a product of multiple originals. We design 1 to 2
quantum bit cloners using the numerical method for finding completely positive
maps approximating a nonphysical one optimally. We discuss the properties of
the so-designed cloners.


title: Universal Gr\"obner Bases for Binary Linear Codes

abstract:
  Each linear code can be described by a code ideal given as the sum of a toric
ideal and a non-prime ideal. In this way, several concepts from the theory of
toric ideals can be translated into the setting of code ideals. It will be
shown that after adjusting some of these concepts, the same inclusion
relationship between the set of circuits, the universal Gr\"obner basis and the
Graver basis holds. Furthermore, in the case of binary linear codes, the
universal Gr\"obner basis will consist of all binomials which correspond to
codewords that satisfy the Singleton bound and a particular rank condition.
This will give rise to a new class of binary linear codes denoted as Singleton
codes.


title:
Density-functional theory for the spin-1 bosons in a one-dimensional
  harmonic trap

abstract:
  We propose the density-functional theory for one-dimensional harmonically
trapped spin-1 bosons in the ground state with repulsive density-density
interaction and anti-ferromagnetic spin-exchange interaction. The density
distributions of spin singlet paired bosons and polarized bosons with different
total polarization for various interaction parameters are obtained by solving
the Kohn-Sham equations which are derived based on the local density
approximation and the Bethe ansatz exact results for homogeneous system.
Non-monotonicity of the central densities is attributed to the competition
between the density interaction and spin-exchange. The results reveal the phase
separation of the paired and polarized bosons, the density profiles of which
respectively approach the Tonks-Girardeau gases of Bose-Bose pairs and scalar
bosons in the case of strong interaction. We give the R-P phase diagram at
strong interaction and find the critical polarization, which paves the way to
direct observe the exotic singlet pairing in spinor gas experimentally.


title: k-connectivity for confined random networks

abstract:
  k-connectivity is an important measure of network robustness and resilience
to random faults and disruptions. We undertake both local and global approaches
to k-connectivity and calculate closed form analytic formulas for the
probability that a confined random network remains fully connected after the
removal of k-1 nodes. Our analysis reveals that k-connectivity is governed by
microscopic details of the network domain such as sharp corners rather than the
macroscopic total volume. Hence, our results can aid in the design of reliable
networks, an important problem in e.g. wireless ad hoc and sensor networks.

categories: cond-mat.dis-nn cs.DM math-ph math.MP math.PR


title:
Axion-like particles: possible hints and constraints from the
  high-energy Universe

abstract:
  The high-energy Universe is potentially a great laboratory for searching new
light bosons such as axion-like particles (ALPs). Cosmic sources are indeed the
scene of violent phenomena that involve strong magnetic field and/or very long
baselines, where the effects of the mixing of photons with ALPs could lead to
observable effects. Two examples are archetypal of this fact, that are the
Universe opacity to gamma-rays and the imprints of astrophysical magnetic
turbulence in the energy spectra of high-energy sources. In the first case,
hints for the existence of ALPs can be proposed whereas the second one is used
to put constraints on the ALP mass and coupling to photons.


title: A decomposition formula for the weighted commutator

abstract:
  We decompose the weighted subobject commutator of M. Gran, G. Janelidze and
A. Ursini as a join of a binary and a ternary commutator.


title:
What really happened on September 15th 2008? Getting The Most from Your
  Personal Information with Memacs

abstract:
  Combining and summarizing meta-data from various kinds of data sources is one
possible solution to the data fragmentation we are suffering from. Multiple
projects have addressed this issue already. This paper presents a new approach
named Memacs. It automatically generates a detailed linked diary of our digital
artifacts scattered across local files of multiple formats as well as data
silos of the internet. Being elegantly simple and open, Memacs uses already
existing visualization features of GNU Emacs and Org-mode to provide a
promising platform for life-logging, Quantified Self movement, and people
looking for advanced Personal Information Management (PIM) in general.


title: Resonant scattering and diffraction beamline P09 at PETRA III

abstract:
  The resonant scattering and diffraction beamline P09 at PETRA III is designed
for X-ray experiments requiring small beams, energy tunability, variable
polarization and high photon flux. It is highly flexible in terms of beam size
and offers full higher harmonic suppression. A state of the art double phase
retarder setup provides variable linear or circular polarization. A high
precision Psi-diffractometer and a heavy load diffractometer in horizontal
Psi-geometry allow the accommodation of a wide variety of sample environments.
A 14 T cryo-magnet is available for scattering experiments in magnetic fields.


title:
Atomic Calligraphy: The Direct Writing of Nanoscale Structures using
  MEMS

abstract:
  We present a micro-electromechanical system (MEMS) based method for the
resist free patterning of nano-structures. Using a focused ion beam (FIB) to
customize larger MEMS machines, we fabricate apertures as small as 50 nm on
plates that can be moved with nanometer precision over an area greater than
20x20 {\mu}m^2. Depositing thermally evaporated gold atoms though the apertures
while moving the plate results in the deposition of nanoscale metal patterns.
Adding a shutter only microns above the aperture, enables high speed control of
not only where but also when atoms are deposited. Using a shutter, different
sized apertures can be selectively opened and closed for nano-structure
fabrication with features ranging from nano- to micrometers in scale. The
ability to evaporate materials with high precision, and thereby fabricate
circuits and structures in situ, enables new kinds of experiments based on the
interactions of a small number of atoms and eventually even single atoms.


title: Rigorous derivation of the rate equations for the epitaxial growth

abstract:
  In the framework of the second-quantization representation of the master
equation governing the irreversible epitaxial growth, exact equations
describing the evolution of the island densities has been obtained. Their
decoupling within a mean field-type approximation with the unknown correlation
functions replaced by capture numbers (CNs) has been used to derive a closed
set of rate equations. The latter has been compared with the exact equations to
obtain rigorous definitions of the CNs. The CN that describes the nucleation of
dimer islands from two mobile monomers has been measured in the exact kinetic
Monte Carlo simulations with the use of the rigorous definition. Strong
disagreement with the literature values calculated within alternative
techniques has been found, especially at low surface coverage. Plausible causes
for the discrepancies are suggested.
  Another important result of the rigorous approach is the rate equation with
the term describing the monomer diffusion. The equation significantly differs
from the widely used equations of this kind known from literature. Arguments in
favour of our approach are given.


title: Interpretation of AMS-02 Results: Correlations among Dark Matter Signals

abstract:
  The AMS-02 collaboration has recently released data on the positron fraction
$e^+/(e^-+e^+)$ up to energies of about 350 GeV. If one insists on interpreting
the observed excess as a dark matter signal, then we find it is best described
by a TeV-scale dark matter annihilating into $\tau^+\tau^-$, although this
situation is already severely constrained by gamma-ray measurements. The
annihilation into $\mu^+\mu^-$ is allowed by gamma-rays more than
$\tau^+\tau^-$, but it gives a poorer fit to \textsc{AMS-02} data. Moreover,
since electroweak corrections induce correlations among the fluxes of stable
particles from dark matter annihilations, the recent AMS-02 data imply a
well-defined prediction for the correlated flux of antiprotons. Under the
assumption that their future measurements will not show any antiproton excess
above the background, the dark matter interpretation of the positron rise will
possibly be ruled out by only making use of data from a single experiment. This
work is the first of a program where we emphasize the role of correlations
among dark matter signals.


title: Lifting of divisible designs

abstract:
  The aim of this paper is to present a construction of $t$-divisible designs
for $t>3$, because such divisible designs seem to be missing in the literature.
To this end, tools such as finite projective spaces and their algebraic
varieties are employed. More precisely, in a first step an abstract
construction, called $t$-lifting, is developed. It starts from a set $X$
containing a $t$-divisible design and a group $G$ acting on $X$. Then several
explicit examples are given, where $X$ is a subset of $PG(n,q)$ and $G$ is a
subgroup of $GL_{n+1}(q)$. In some cases $X$ is obtained from a cone with a
Veronesean or an $h$-sphere as its basis. In other examples $X$ arises from a
projective embedding of a Witt design. As a result, for any integer $t\geq 2$
infinitely many non-isomorphic $t$-divisible designs are found.


title: Divisible designs from twisted dual numbers

abstract:
  The generalized chain geometry over the local ring $K(\epsilon;\sigma)$ of
twisted dual numbers, where $K$ is a finite field, is interpreted as a
divisible design obtained from an imprimitive group action. Its combinatorial
properties as well as a geometric model in 4-space are investigated.


title: Geometric Entanglement in Topologically Ordered States

abstract:
  Here we investigate the connection between topological order and the
geometric entanglement, as measured by the logarithm of the overlap between a
given state and its closest product state of blocks. We do this for a variety
of topologically-ordered systems such as the toric code, double semion, color
code, and quantum double models. As happens for the entanglement entropy, we
find that for sufficiently large block sizes the geometric entanglement is, up
to possible sub-leading corrections, the sum of two contributions: a bulk
contribution obeying a boundary law times the number of blocks, and a
contribution quantifying the underlying pattern of long-range entanglement of
the topologically-ordered state. This topological contribution is also present
in the case of single-spin blocks in most cases, and constitutes an alternative
characterisation of topological order for these quantum states based on a
multipartite entanglement measure. In particular, we see that the topological
term for the 2D color code is twice as much as the one for the toric code, in
accordance with recent renormalization group arguments. Motivated by this, we
also derive a general formalism to obtain upper- and lower-bounds to the
geometric entanglement of states with a non-Abelian symmetry, and which we use
to analyse quantum double models. Furthermore, we also analyse the robustness
of the topological contribution using renormalization and perturbation theory
arguments, as well as a numerical estimation for small systems. Some of our
results rely on the ability to disentangle single sites from the system, which
is always possible in our framework. Aditionally, we relate our results to the
relative entropy of entanglement in topological systems, and discuss some
tensor network numerical approaches that could be used to extract the
topological contribution for large systems beyond exactly-solvable models.


title: Blocking sets in chain geometries

abstract:
  In this paper we give some basic results on blocking sets on minimum size for
a finite chain geometry.


title:
Glassy low-energy spin fluctuations and anisotropy gap in
  La1.88Sr0.12CuO4

abstract:
  We present high-resolution triple-axis neutron scattering studies of the
high-temperature superconductor La1.88Sr0.12CuO4 (Tc=27 K). The temperature
dependence of the low-energy incommensurate magnetic fluctuations reveals
distinctly glassy features. The glassiness is confirmed by the difference
between the ordering temperature TN ~ Tc inferred from elastic neutron
scattering and the freezing temperature Tf ~ 11 K obtained from muon spin
rotation studies. The magnetic field independence of the observed excitation
spectrum as well as the observation of a partial suppression of magnetic
spectral weight below 0.75 meV for temperatures smaller than Tf, indicate that
the stripe frozen state is capable of supporting a spin anisotropy gap, of a
magnitude similar to that observed in the spin and charge stripe ordered ground
state of La1.875Ba0.125CuO4. The difference between TN and Tf implies that the
significant enhancement in a magnetic field of nominally elastic incommensurate
scattering is caused by strictly in-elastic scattering -- at least in the
temperature range between Tf and Tc -- which is not resolved in the present
experiment. Combining the results obtained from our study of La1.88Sr0.12CuO4
with a critical reappraisal of published neutron scattering work on samples
with chemical composition close to p=0.12, where local probes indicate a sharp
maximum in Tf(p), we arrive at the view that the low-energy fluctuations are
strongly dependent on composition in this regime, with anisotropy gaps
dominating only sufficiently close to p=0.12 and superconducting spin gaps
dominating elsewhere.


title:
On Exceptional Times for generalized Fleming-Viot Processes with
  Mutations

abstract:
  If $\mathbf Y$ is a standard Fleming-Viot process with constant mutation rate
(in the infinitely many sites model) then it is well known that for each $t>0$
the measure $\mathbf Y_t$ is purely atomic with infinitely many atoms. However,
Schmuland proved that there is a critical value for the mutation rate under
which almost surely there are exceptional times at which $\mathbf Y$ is a
finite sum of weighted Dirac masses. In the present work we discuss the
existence of such exceptional times for the generalized Fleming-Viot processes.
In the case of Beta-Fleming-Viot processes with index $\alpha\in\,]1,2[$ we
show that - irrespectively of the mutation rate and $\alpha$ - the number of
atoms is almost surely always infinite. The proof combines a Pitman-Yor type
representation with a disintegration formula, Lamperti's transformation for
self-similar processes and covering results for Poisson point processes.


title: From pentacyclic coordinates to chain geometries, and back

abstract:
  Starting with the classical circle geometry of Sophus Lie, we give a survey
about some of the developments in the area of chain geometries during the last
three decades.


title: Incidence and Combinatorial Properties of Linear Complexes

abstract:
  In this paper a generalisation of the notion of polarity is exhibited which
allows to completely describe, in an incidence-geometric way, the linear
complexes of $h$-subspaces. A generalised polarity is defined to be a partial
map which maps $(h-1)$-subspaces to hyperplanes, satisfying suitable linearity
and reciprocity properties. Generalised polarities with the null property give
rise to a linear complexes and vice versa. Given that there exists for $h>1$ a
linear complex of $h$-subspaces which contains no star --this seems to be an
open problem over an arbitrary ground field --the combinatorial structure of a
partition of the line set of the projective space into non-geometric spreads of
its hyperplanes can be obtained. This line partition has an additional
linearity property which turns out to be characteristic.


title: Diameter preserving surjections in the geometry of matrices

abstract:
  We consider a class of graphs subject to certain restrictions, including the
finiteness of diameters. Any surjective mapping $\phi:\Gamma\to\Gamma'$ between
graphs from this class is shown to be an isomorphism provided that the
following holds: Any two points of $\Gamma$ are at a distance equal to the
diameter of $\Gamma$ if, and only if, their images are at a distance equal to
the diameter of $\Gamma'$. This result is then applied to the graphs arising
from the adjacency relations of spaces of rectangular matrices, spaces of
Hermitian matrices, and Grassmann spaces (projective spaces of rectangular
matrices).


title:
Domain Specific Language for Geometric Relations between Rigid Bodies
  targeted to robotic applications

abstract:
  This paper presents a DSL for geometric relations between rigid bodies such
as relative position, orientation, pose, linear velocity, angular velocity, and
twist. The DSL is the formal model of the recently proposed semantics for the
standardization of geometric relations between rigid bodies, referred to as
`geometric semantics'. This semantics explicitly states the
coordinate-invariant properties and operations, and, more importantly, all the
choices that are made in coordinate representations of these geometric
relations. This results in a set of concrete suggestions for standardizing
terminology and notation, allowing programmers to write fully unambiguous
software interfaces, including automatic checks for semantic correctness of all
geometric operations on rigid-body coordinate representations.
  The DSL is implemented in two different ways: an external DSL in Xcore and an
internal DSL in Prolog. Besides defining a grammar and operations, the DSL also
implements constraints. In the Xcore model, the Object Constraint Language
language is used, while in the Prolog model, the constraint are natively
modelled in Prolog.
  This paper discusses the implemented DSL and the tools developed on top of
this DSL. In particular an editor, checking the semantic constraints and
providing semantic meaningful errors during editing is proposed.


title: A composition theorem for the Fourier Entropy-Influence conjecture

abstract:
  The Fourier Entropy-Influence (FEI) conjecture of Friedgut and Kalai [FK96]
seeks to relate two fundamental measures of Boolean function complexity: it
states that $H[f] \leq C Inf[f]$ holds for every Boolean function $f$, where
$H[f]$ denotes the spectral entropy of $f$, $Inf[f]$ is its total influence,
and $C > 0$ is a universal constant. Despite significant interest in the
conjecture it has only been shown to hold for a few classes of Boolean
functions.
  Our main result is a composition theorem for the FEI conjecture. We show that
if $g_1,...,g_k$ are functions over disjoint sets of variables satisfying the
conjecture, and if the Fourier transform of $F$ taken with respect to the
product distribution with biases $E[g_1],...,E[g_k]$ satisfies the conjecture,
then their composition $F(g_1(x^1),...,g_k(x^k))$ satisfies the conjecture. As
an application we show that the FEI conjecture holds for read-once formulas
over arbitrary gates of bounded arity, extending a recent result [OWZ11] which
proved it for read-once decision trees. Our techniques also yield an explicit
function with the largest known ratio of $C \geq 6.278$ between $H[f]$ and
$Inf[f]$, improving on the previous lower bound of 4.615.


title: Erinnerungen an Heinrich Brauner (1928--1990)

abstract: Recollections of the Austrian geometer Heinrich Brauner (in German).


title: INTEGRAL IBIS/ISGRI energy calibration in OSA 10

abstract:
  We present the new energy calibration of the ISGRI detector onboard INTEGRAL,
that has been implemented in the Offline Scientific Analysis (OSA) version 10.
With the previous OSA 9 version, a clear departure from stability of both W and
22Na background lines was observed after MJD 54307 (revolution ~583). To solve
this problem, the energy correction in OSA 10 uses: 1) a new description for
the gain depending on the time and the pulse rise time, 2) an improved
temperature correction per module, and 3) a varying shape of the low threshold,
corrected for the change in energy resolution. With OSA 10, both background
lines show a remarkably stable behavior with a relative energy variation below
1% around the nominal position (>6% in OSA 9), and the energy reconstruction at
low energies is more stable compared to previous OSA versions. We extracted
Crab light curves with ISGRI in different energy bands using all available data
since the beginning of the mission, and found a very good agreement with the
currently operational hard X-ray instruments Swift/BAT and Fermi/GBM.


title: A Direct Sampler for G-Wishart Variates

abstract:
  The G-Wishart distribution is the conjugate prior for precision matrices that
encode the conditional independencies of a Gaussian graphical model. While the
distribution has received considerable attention, posterior inference has
proven computationally challenging, in part due to the lack of a direct
sampler. In this note, we rectify this situation. The existence of a direct
sampler offers a host of new possibilities for the use of G-Wishart variates.
We discuss one such development by outlining a new transdimensional model
search algorithm--which we term double reversible jump--that leverages this
sampler to avoid normalizing constant calculation when comparing graphical
models. We conclude with two short studies meant to investigate our algorithm's
validity.


title:
On the complexity of strong Nash equilibrium: Hard-to-solve instances
  and smoothed complexity

abstract:
  The computational characterization of game-theoretic solution concepts is a
central topic in artificial intelligence, with the aim of developing
computationally efficient tools for finding optimal ways to behave in strategic
interactions. The central solution concept in game theory is Nash equilibrium
(NE). However, it fails to capture the possibility that agents can form
coalitions (even in the 2-agent case). Strong Nash equilibrium (SNE) refines NE
to this setting. It is known that finding an SNE is NP-complete when the number
of agents is constant. This hardness is solely due to the existence of
mixed-strategy SNEs, given that the problem of enumerating all pure-strategy
SNEs is trivially in P. Our central result is that, in order for a game to have
at least one non-pure-strategy SNE, the agents' payoffs restricted to the
agents' supports must, in the case of 2 agents, lie on the same line, and, in
the case of n agents, lie on an (n - 1)-dimensional hyperplane. Leveraging this
result, we provide two contributions. First, we develop worst-case instances
for support-enumeration algorithms. These instances have only one SNE and the
support size can be chosen to be of any size-in particular, arbitrarily large.
Second, we prove that, unlike NE, finding an SNE is in smoothed polynomial
time: generic game instances (i.e., all instances except knife-edge cases) have
only pure-strategy SNEs.


title:
Reply to "Comment on `Optimal probe wave function of weak-value
  amplification' "

abstract:
  It is pointed out that the "counter example" presented in the Comment is a
family of probe wave functions which are increasingly broad as the shift
becomes large. Furthermore, the author's variational calculation is not correct
in the sense that we have to gauge fix the freedom of the phase translation. It
is shown that there are two kinds of solutions, normalizable and
un-normalizable. The former is our optimal solution, and the latter is what he
found. It seems only the former is relevant from a practical point of view.


title:
Effect of stacking faults on the magnetocrystalline anisotropy of hcp
  Co: a first-principles study

abstract:
  In terms of the fully relativistic screened Korringa-Kohn-Rostoker method we
investigate the effect of stacking faults on the magnetic properties of
hexagonal close-packed cobalt. In particular, we consider the formation energy
and the effect on the magnetocrystalline anisotropy energy (MAE) of four
different stacking faults in hcp cobalt -- an intrinsic growth fault, an
intrinsic deformation fault, an extrinsic fault and a twin-like fault. We find
that the intrinsic growth fault has the lowest formation energy, in good
agreement with previous first-principles calculations. With the exception of
the intrinsic deformation fault which has a positive impact on the MAE, we find
that the presence of a stacking fault generally reduces the MAE of bulk Co.
Finally, we consider a pair of intrinsic growth faults and find that their
effect on the MAE is not additive, but synergic.


title: Wave Extremes in the North East Atlantic from Ensemble Forecasts

abstract:
  A method for estimating return values from ensembles of forecasts at advanced
lead times is presented. Return values of significant wave height in the
North-East Atlantic, the Norwegian Sea and the North Sea are computed from
archived +240-h forecasts of the ECMWF ensemble prediction system (EPS) from
1999 to 2009.
  We make three assumptions: First, each forecast is representative of a
six-hour interval and collectively the data set is then comparable to a time
period of 226 years. Second, the model climate matches the observed
distribution, which we confirm by comparing with buoy data. Third, the ensemble
members are sufficiently uncorrelated to be considered independent realizations
of the model climate. We find anomaly correlations of 0.20, but peak events
(>P97) are entirely uncorrelated. By comparing return values from individual
members with return values of subsamples of the data set we also find that the
estimates follow the same distribution and appear unaffected by correlations in
the ensemble. The annual mean and variance over the 11-year archived period
exhibit no significant departures from stationarity compared with a recent
reforecast, i.e., there is no spurious trend due to model upgrades.
  EPS yields significantly higher return values than ERA-40 and ERA-Interim and
is in good agreement with the high-resolution hindcast NORA10, except in the
lee of unresolved islands where EPS overestimates and in enclosed seas where it
is biased low. Confidence intervals are half the width of those found for
ERA-Interim due to the magnitude of the data set.


title: Ho and Fe magnetic ordering in multiferroic HoFe3(BO3)O4

abstract:
  Resonant and non-resonant X-ray scattering studies on HoFe3(BO3)O4 reveal
competing magnetic ordering of Ho and Fe moments. Temperature and X-ray
polarization dependent measurements employed at the Ho L3 edge directly reveal
a spiral spin order of the induced Ho moments in the ab-plane propagating along
the c-axis, a screw-type magnetic structure. At about 22.5 K the Fe spins are
observed to rotate within the basal plane inducing spontaneous electric
polarization, P. Components of P in the basal plane and along the c-axis can be
scaled with the separated magnetic X-ray scattering intensities of the Fe and
Ho magnetic sublattices, respectively.


title:
The Graph Grammar Library - a generic framework for chemical graph
  rewrite systems

abstract:
  Graph rewrite systems are powerful tools to model and study complex problems
in various fields of research. Their successful application to chemical
reaction modelling on a molecular level was shown but no appropriate and simple
system is available at the moment.
  The presented Graph Grammar Library (GGL) implements a generic Double Push
Out approach for general graph rewrite systems. The framework focuses on a high
level of modularity as well as high performance, using state-of-the-art
algorithms and data structures, and comes with extensive documentation. The
large GGL chemistry module enables extensive and detailed studies of chemical
systems. It well meets the requirements and abilities envisioned by Yadav et
al. (2004) for such chemical rewrite systems. Here, molecules are represented
as undirected labeled graphs while chemical reactions are described by
according graph grammar rules. Beside the graph transformation, the GGL offers
advanced cheminformatics algorithms for instance to estimate energies
ofmolecules or aromaticity perception. These features are illustrated using a
set of reactions from polyketide chemistry a huge class of natural compounds of
medical relevance.
  The graph grammar based simulation of chemical reactions offered by the GGL
is a powerful tool for extensive cheminformatics studies on a molecular level.
The GGL already provides rewrite rules for all enzymes listed in the KEGG
LIGAND database is freely available at
http://www.tbi.univie.ac.at/software/GGL/.


title: Trap-free manipulation in the Landau-Zener system

abstract:
  The analysis of traps, i.e., locally but not globally optimal controls, for
quantum control systems has attracted a great interest in recent years. The
central problem that has been remained open is to demonstrate for a given
system either existence or absence of traps. We prove the absence of traps and
hence completely solve this problem for the important tasks of unconstrained
manipulation of the transition probability and unitary gate generation in the
Landau-Zener system---a system with a wide range of applications across
physics, chemistry and biochemistry. This finding provides the first example of
a controlled quantum system which is completely free of traps. We also discuss
the impact of laboratory constraints due to decoherence, noise in the control
pulse, and restrictions on the available controls which when being sufficiently
severe can produce traps.


title: Controlling plasmonic Bloch modes on periodic nanostructures

abstract:
  We study and actively control the coherent properties of Surface Plasmon
Polaritons (SPPs) optically exited on a nano-hole array. Amplitude and phase of
the optical excitation are externally controlled via a digital spatial light
modulator (SLM) and SPP interference fringe patterns are observed with high
contrast. Our interferometric observations revel SPPs dressed with the Bloch
modes of the periodic nano-structure. The momentum associated with these
Dressed Plasmons (DP) is highly dependent on the grating period and fully
matches our theoretical predictions. We show that the momentum of DP waves can
in principle exceed the SPP momentum. Actively controlling DP waves via
programmable phase patterns offers the potential for high field confinement
applicable in sensing, Surface Enhanced Raman Scattering and plasmonic
structured illumination microscopy.


title: Randomness-Efficient Rumor Spreading

abstract:
  We study the classical rumor spreading problem, which is used to spread
information in an unknown network with $n$ nodes. We present the first protocol
for any expander graph $G$ with $n$ nodes and minimum degree $\Theta(n)$ such
that, the protocol informs every node in $O(\log n)$ rounds with high
probability, and uses $O(\log n\log\log n)$ random bits in total. The runtime
of our protocol is tight, and the randomness requirement of $O(\log n\log\log
n)$ random bits almost matches the lower bound of $\Omega(\log n)$ random bits.
We further study rumor spreading protocols for more general graphs, and for
several graph topologies our protocols are as fast as the classical protocol
and use $\tilde{O}(\log n)$ random bits in total, in contrast to $O(n\log^2n)$
random bits used in the well-known rumor spreading push protocol. These results
together give us almost full understanding of the randomness requirement for
this basic epidemic process.
  Our protocols rely on a novel reduction between rumor spreading processes and
branching programs, and this reduction provides a general framework to
derandomize these complex and distributed epidemic processes. Interestingly,
one cannot simply apply PRGs for branching programs as rumor spreading process
is not characterized by small-space computation. Our protocols require the
composition of several pseudorandom objects, e.g. pseudorandom generators, and
pairwise independent generators. Besides designing rumor spreading protocols,
the techniques developed here may have applications in studying the randomness
complexity of distributed algorithms.


title: Universal Democracy Instead of Anarchy

abstract:
  We propose for the flavour structure of both the quark and lepton sectors,
the principle of Universal Democracy (UD), which reflects the presence of a
$Z_3$ symmetry. In the quark sector, we emphasize the importance of UD for
obtaining small mixing and flavour alignment, while in the lepton sector, large
mixing, including the recently measured value of $U_{e3}$, is obtained in the
UD framework through the seesaw mechanism. An interesting correlation between
the values of $U_{e3}$ and $\sin^2(\theta_{23})$ is pointed out, with the
prediction of $\sin^2(\theta_{23})\approx 0.42$ in the region where $U_{e3}$ is
in agreement with the DAYA-BAY experiment.


title: Semiclassical Ehrenfest Paths

abstract:
  Trajectories are a central concept in our understanding of classical
phenomena and also in rationalizing quantum mechanical effects. In this work we
provide a way to determine semiclassical paths, approximations to quantum
averages in phase space, directly from classical trajectories. We avoid the
need of intermediate steps, like particular solutions to the Schroedinger
equation or numerical integration in phase space by considering the system to
be initially in a coherent state and by assuming that its early dynamics is
governed by the Heller semiclassical approximation. Our result is valid for
short propagation times only, but gives non-trivial information on the
quantum-classical transition.


title:
Formation of chondrules in radiative shock waves I. First results,
  spherical dust particles, stationary shocks

abstract:
  The formation of chondrules in the protoplanetary nebulae causes many
questions concerning the formation process, the source of energy for melting
the rims, and the composition of the origin material. The aim of this work is
to explore the heating of the chondrule in a single precursor as is typical for
radiation hydrodynamical shock waves. We take into account the gas-particle
friction for the duration of the shock transition and calculate the heat
conduction into the chondrules. These processes are located in the
protoplanetary nebulae at a region around 2.5 AU, which is considered to be the
most likely place of chondrule formation. The present models are a first step
towards computing radiative shock waves occurring in a particle-rich
environment. We calculated the shock waves using one-dimensional,
time-independent equations of radiation hydrodynamics involving realistic gas
and dust opacities and gas-particle friction. The evolution of spherical
chondrules was followed by solving the heat conduction equation on an adaptive
grid. The results for the shock-heating event are consistent with the
cosmochemical constraints of chondrule properties. The calculations yield a
relative narrow range for density or temperature to meet the requested heating
rates of $R > 10^4\,K\, h^{-1}$ as extracted from cosmochemical constraints.
Molecular gas, opacities with dust, and a protoplanetary nebula with accretion
are necessary requirements for a fast heating process. The thermal structure in
the far post-shock region is not fully consistent with experimental constraints
on chondrule formation since the models do not include additional molecular
cooling processes.


title:
A note on a topological approach to the $\mu$-constant problem in
  dimension 2

abstract:
  We provide an example, which shows that studying homological and homotopical
properties of cobordisms between arbitrary, that is not necessarily negative,
graph manifolds is not enough to prove the $\mu$-constant conjecture of Le Dung
Trang in complex dimension 2.


title: Ellerman bombs: fallacies, fads, usage

abstract:
  Ellerman bombs are short-lived brightenings of the outer wings of Halpha that
occur in active regions with much flux emergence. We point out fads and
fallacies in the extensive Ellerman bomb literature, discuss their appearance
in various spectral diagnostics, and advocate their use as indicators of field
reconfiguration in active-region topography using AIA 1700 A images.


title:
Making Waves Round a Structured Cloak: Lattices, Negative Refraction and
  Fringes

abstract:
  Using the framework of transformation optics, this paper presents a detailed
analysis of a non-singular square cloak for acoustic, out-of-plane shear
elastic, and electromagnetic waves. The generating map is examined in detail
and linked to the material properties of the cloak. Analysis of wave
propagation through the cloak is presented and accompanied by numerical
illustrations. The efficacy of the regularised cloak is demonstrated and an
objective numerical measure of the quality of the cloaking effect is provided.
It is demonstrated that the cloaking effect persists over a wide range of
frequencies. As a demonstration of the effectiveness of the regularised cloak,
a Young's double slit experiment is presented. The stability of the
interference pattern is examined when a cloaked and uncloaked obstacle are
successively placed in front of one of the apertures. This novel link with a
well-known quantum mechanical experiment provides an additional method through
which the quality of cloaks may be examined. In the second half of the paper,
it is shown that an approximate cloak may be constructed using a discrete
lattice structure. The geometry and material properties of the lattice are
derived from the continuum cloak. The efficiency of the approximate lattice
cloak is analysed and a series of illustrative simulations presented. It is
demonstrated that effective cloaking may be obtained by using a relatively
simple lattice structure, particularly in the low frequency regime.


title:
Bispinor Auxiliary Fields in Duality-Invariant Electrodynamics
  Revisited: The U(N) Case

abstract:
  We update and detail the formulation of the duality-invariant systems of N
interacting abelian gauge fields with N auxiliary bispinor fields added. In
this setting, the self-duality amounts to U(N) invariance of the nonlinear
interaction of the auxiliary fields. The U(N) self-dual Lagrangians arise after
solving the nonlinear equations of motion for the auxiliary fields. We also
elaborate on a new extended version of the bispinor field formulation involving
some additional scalar auxiliary fields and study U(N) invariant interactions
with derivatives of the auxiliary bispinor fields. Such interactions generate
higher-derivative U(N) self-dual theories.


title:
The Effects of Inhomogeneities within Colliding Flows on the Formation
  and Evolution of Molecular Clouds

abstract:
  Observational evidence from local star-forming regions mandates that star
formation occurs shortly after, or even during, molecular cloud formation.
Models of the formation of molecular clouds in large-scale converging flows
have identified the physical mechanisms driving the necessary rapid
fragmentation. They also point to global gravitational collapse driving
supersonic turbulence in molecular clouds. Previous cloud formation models have
focused on turbulence generation, gravitational collapse, magnetic fields, and
feedback. Here, we explore the effect of structure in the flow on the resulting
clouds and the ensuing gravitational collapse. We compare two extreme cases,
one with a collision between two smooth streams, and one with streams
containing small clumps. We find that structured converging flows lead to a
delay of local gravitational collapse ("star formation"). Thus, more gas has
time to accumulate, eventually leading to a strong global collapse, and thus to
a high star formation rate. Uniform converging flows fragment hydrodynamically
early on, leading to the rapid onset of local gravitational collapse and an
overall low sink formation rate.


title:
Theory-based Benchmarking of the Blended Force-Based Quasicontinuum
  Method

abstract:
  We formulate an atomistic-to-continuum coupling method based on blending
atomistic and continuum forces. Our precise choice of blending mechanism is
informed by theoretical predictions. We present a range of numerical
experiments studying the accuracy of the scheme, focusing in particular on its
stability. These experiments confirm and extend the theoretical predictions,
and demonstrate a superior accuracy of B-QCF over energy-based blending
schemes.


title:
Supermassive Black Hole Formation at High Redshifts via Direct Collapse:
  Physical Processes in the Early Stage

abstract:
  We use numerical simulations to explore whether direct collapse can lead to
the formation of SMBH seeds at high-z. We follow the evolution of gas within DM
halos of 2 x 10^8 Mo and 1 kpc. We adopt cosmological density profiles and
j-distributions. Our goal is to understand how the collapsing flow overcomes
the centrifugal barrier and whether it is subject to fragmentation. We find
that the collapse leads either to a central runaway or to off-center
fragmentation. A disk-like configuration is formed inside the centrifugal
barrier. For more cuspy DM distribution, the gas collapses more and experiences
a bar-like perturbation and a central runaway. We have followed this inflow
down to ~10^{-4} pc. The flow remains isothermal and the specific angular
momentum is efficiently transferred by gravitational torques in a cascade of
nested bars. This cascade supports a self-similar, disk-like collapse. In the
collapsing phase, virial supersonic turbulence develops and fragmentation is
damped. For larger initial DM cores the timescales become longer. In models
with more organized initial rotation, a torus forms and appears to be supported
by turbulent motions. The evolution depends on the competition between two
timescales, corresponding to the onset of the central runaway and off-center
fragmentation. For less organized rotation, the torus is greatly weakened, the
central accretion timescale is shortened, and off-center fragmentation is
suppressed --- triggering the central runaway even in previously `stable'
models. The resulting SMBH masses lie in the range 2 x 10^4 Mo - 2 x 10^6 Mo,
much higher than for Population III remnants. We argue that the above upper
limit appears to be more realistic mass. Corollaries of this model include a
possible correlation between SMBH and DM halo masses, and similarity between
the SMBH and halo mass functions, at time of formation.


title:
Change in the mean in the domain of attraction of the normal law via
  Darling-Erd\H{o}s theorems

abstract:
  This paper studies the problem of testing the null assumption of no-change in
the mean of chronologically ordered independent observations on a random
variable $X$ {\it versus} the at most one change in the mean alternative
hypothesis. The approach taken is via a Darling-Erd\H{o}s type self-normalized
maximal deviation between sample means before and sample means after possible
times of a change in the expected values of the observations of a random
sample. Asymptotically, the thus formulated maximal deviations are shown to
have a standard Gumbel distribution under the null assumption of no change in
the mean. A first such result is proved under the condition that $EX^2\log\log
(|X|+1)<\infty$, while in the case of a second one, $X$ is assumed to be in a
specific class of the domain of attraction of the normal law, possibly with
infinite variance.


title: Remark on the Serre-Swan theorem for graded manifolds

abstract:
  Combining the Batchelor theorem and the Serre-Swan theorem, we come to that,
given a smooth manifold $X$, a graded commutative $C^\infty(X)$-algebra $\cA$
is isomorphic to the structure ring of a graded manifold with a body $X$ iff it
is the exterior algebra of some projective $C^\infty(X)$-module of finite rank.
In particular, it follows that odd fields in field theory on a smooth manifold
$X$ can be represented by graded functions on some graded manifold with body
$X$.


title: Quasi-Hamiltonian bookkeeping of WZNW defects

abstract:
  We interpret the chiral WZNW model with general monodromy as an infinite
dimensional quasi-Hamiltonian dynamical system. This interpretation permits to
explain the totality of complicated cross-terms in the symplectic structures of
various WZNW defects solely in terms of the single concept of the
quasi-Hamiltonian fusion. Translated from the WZNW language into that of the
moduli space of flat connections on Riemann surfaces, our result gives a
compact and transparent characterisation of the symplectic structure of the
moduli space of flat connections on a surface with k handles, n boundaries and
m Wilson lines.


title:
Threshold resummation for polarized (semi-)inclusive deep inelastic
  scattering

abstract:
  We explore the effects of the resummation of large logarithmic perturbative
corrections to double-longitudinal spin asymmetries for inclusive and
semi-inclusive deep inelastic scattering in fixed-target experiments. We find
that the asymmetries are overall rather robust with respect to the inclusion of
the resummed higher-order terms. Significant effects are observed at fairly
high values of x, where resummation tends to decrease the spin asymmetries.
This effect turns out to be more pronounced for semi-inclusive scattering. We
also investigate the potential impact of resummation on the extraction of
polarized valence quark distributions in dedicated high-x experiments.


title: Report on the EuDML external cooperation model

abstract:
  One of the main tasks of the European Digital Mathematics Library project was
to define a cooperation model with a variety of stakeholders that would allow
building a reliable and durable global reference library, aiming to be
eventually exhaustive. In this paper we present the EuDML external cooperation
model and the business plan as the basis for its sustainability and further
development.


title:
Modeling of electron emission processes accompanying
  Radon-$\alpha$-decays within electrostatic spectrometers

abstract:
  Electrostatic spectrometers utilized in high-resolution beta-spectroscopy
studies such as in the Karlsruhe Tritium Neutrino (KATRIN) experiment have to
operate with a background level of less than 10^(-2) counts per second. This
limit can be exceeded by even a small number of Rn-219 or Rn-220 atoms being
emanated into the volume and undergoing alpha-decay there. In this paper we
present a detailed model of the underlying background-generating processes via
electron emission by internal conversion, shake-off and relaxation processes in
the atomic shells of the Po-215 and Po-216 daughters. The model yields electron
energy spectra up to 400 keV and electron multiplicities of up to 20 which are
compared to experimental data.


title:
An alternative proof of Wigner theorem on quantum transformations based
  on elementary complex analysis

abstract:
  According to Wigner theorem, transformations of quantum states which preserve
the probabilities are either unitary or antiunitary. This short communication
presents an elementary proof of this theorem that significantly departs from
the numerous ones already existing in the literature. The main line of the
argument remains valid even in quantum field theory where Hilbert spaces are
non-separable.


title:
On the loss of the semimartingale property at the hitting time of a
  level

abstract:
  This paper studies the loss of the semimartingale property of the process
$g(Y)$ at the time a one-dimensional diffusion $Y$ hits a level, where $g$ is a
difference of two convex functions. We show that the process $g(Y)$ can fail to
be a semimartingale in two ways only, which leads to a natural definition of
non-semimartingales of the \textit{first} and \textit{second kind}. We give a
deterministic if and only if condition (in terms of $g$ and the coefficients of
$Y$) for $g(Y)$ to fall into one of the two classes of processes, which yields
a characterisation for the loss of the semimartingale property. A number of
applications of the results in the theory of stochastic processes and real
analysis are given: e.g. we construct an adapted diffusion $Y$ on $[0,\infty)$
and a \emph{predictable} finite stopping time $\zeta$, such that $Y$ is a
semimartingale on the stochastic interval $[0,\zeta)$, continuous at $\zeta$
and constant after $\zeta$, but is \emph{not} a semimartingale on $[0,\infty)$.


title: A universal approach to the calculation of the transit light curves

abstract:
  We have developed a universal approach to compute accurately the brightness
of eclipsing binary systems during the transit of a planet in front of the
stellar disk. This approach is uniform for all values of the system parameters
and applicable to most limb-darkening laws used in astrophysics. In the cases
of linear and quadratic limb-darkening laws we obtained analytical expressions
for the light curve and its derivatives in terms of elementary functions,
elliptic integrals and piecewise-defined function of one variable. In the cases
of logarithmic and square root laws of limb darkening the flux and its
derivatives were expressed in terms of integrals which can be efficiently
computed using Gaussian quadrature formula, taking into account singularities
of the integrand.


title:
Validation of a model for Radon-induced background processes in
  electrostatic spectrometers

abstract:
  The Karlsruhe Tritium Neutrino (KATRIN) experiment investigating tritium
beta-decay close to the endpoint with unprecedented precision has stringent
requirements on the background level of less than 10^(-2) counts per second.
Electron emission during the alpha-decay of Rn-219 and Rn-220 atoms in the
electrostatic spectrometers of KATRIN is a serious source of background
exceeding this limit. In this paper we compare extensive simulations of
Rn-induced background to specific measurements with the KATRIN pre-spectrometer
to fully characterize the observed Rn-background rates and signatures and
determine generic Rn emanation rates from the pre-spectrometer bulk material
and its vacuum components.


title: Groups definable in two orthogonal sorts

abstract:
  This work can be thought as a contribution to the model theory of group
extensions. We study the groups G which are interpretable in the disjoint union
of two structures (seen as a two-sorted structure). We show that if one of the
two structures is superstable of finite Lascar rank and the Lascar rank is
definable, then G is an extension of a group internal to the (possibly)
unstable sort by a definable subgroup internal to the stable sort. In the final
part of the paper we show that if the unstable sort is an o-minimal expansion
of the reals, then G has a natural Lie structure and the extension is a
topological cover.


title:
Algebraic independence of elements in immediate extensions of valued
  fields

abstract:
  Refining a constructive combinatorial method due to MacLane and Schilling, we
give several criteria for a valued field that guarantee that all of its maximal
immediate extensions have infinite transcendence degree. If the value group of
the field has countable cofinality, then these criteria give the same
information for the completions of the field. The criteria have applications to
the classification of valuations on rational function fields. We also apply the
criteria to the question which extensions of a maximal valued field, algebraic
or of finite transcendence degree, are again maximal. In the case of valued
fields of infinite $p$-degree, we obtain the worst possible examples of
nonuniqueness of maximal immediate extensions: fields which admit an algebraic
maximal immediate extension as well as one of infinite transcendence degree.


title:
Planetary Nebula Spectrograph survey of S0 galaxy kinematics. II. Clues
  to the origins of S0 galaxies

abstract:
  The stellar kinematics of the spheroids and discs of S0 galaxies contain
clues to their formation histories. Unfortunately, it is difficult to
disentangle the two components and to recover their stellar kinematics in the
faint outer parts of the galaxies using conventional absorption line
spectroscopy. This paper therefore presents the stellar kinematics of six S0
galaxies derived from observations of planetary nebulae (PNe), obtained using
the Planetary Nebula Spectrograph. To separate the kinematics of the two
components, we use a maximum-likelihood method that combines the discrete
kinematic data with a photometric component decomposition. The results of this
analysis reveal that: the discs of S0 galaxies are rotationally supported;
however, the amount of random motion in these discs is systematically higher
than in comparable spiral galaxies; and the S0s lie around one magnitude below
the Tully--Fisher relation for spiral galaxies, while their spheroids lie
nearly one magnitude above the Faber--Jackson relation for ellipticals. All of
these findings are consistent with a scenario in which spirals are converted
into S0s through a process of mild harassment or "pestering," with their discs
somewhat heated and their spheroid somewhat enhanced by the conversion process.
In such a scenario, one might expect the properties of S0s to depend on
environment. We do not see such an effect in this fairly small sample, although
any differences would be diluted by the fact that the current location does not
necessarily reflect the environment in which the transformation occurred.
Similar observations of larger samples probing a broader range of environments,
coupled with more detailed modelling of the transformation process to match the
wide range of parameters that we have shown can now be measured, should take us
from these first steps to the definitive answer as to how S0 galaxies form.


title: On Size and Power of Heteroskedasticity and Autocorrelation Robust Tests

abstract:
  Testing restrictions on regression coefficients in linear models often
requires correcting the conventional F-test for potential heteroskedasticity or
autocorrelation amongst the disturbances, leading to so-called
heteroskedasticity and autocorrelation robust test procedures. These procedures
have been developed with the purpose of attenuating size distortions and power
deficiencies present for the uncorrected F-test. We develop a general theory to
establish positive as well as negative finite-sample results concerning the
size and power properties of a large class of heteroskedasticity and
autocorrelation robust tests. Using these results we show that
nonparametrically as well as parametrically corrected F-type tests in time
series regression models with stationary disturbances have either size equal to
one or nuisance-infimal power equal to zero under very weak assumptions on the
covariance model and under generic conditions on the design matrix. In addition
we suggest an adjustment procedure based on artificial regressors. This
adjustment resolves the problem in many cases in that the so-adjusted tests do
not suffer from size distortions. At the same time their power function is
bounded away from zero. As a second application we discuss the case of
heteroskedastic disturbances.


title:
Nonparametric estimation of the tree structure of a nested Archimedean
  copula

abstract:
  One of the features inherent in nested Archimedean copulas, also called
hierarchical Archimedean copulas, is their rooted tree structure. A
nonparametric, rank-based method to estimate this structure is presented. The
idea is to represent the target structure as a set of trivariate structures,
each of which can be estimated individually with ease. Indeed, for any three
variables there are only four possible rooted tree structures and, based on a
sample, a choice can be made by performing comparisons between the three
bivariate margins of the empirical distribution of the three variables. The set
of estimated trivariate structures can then be used to build an estimate of the
target structure. The advantage of this estimation method is that it does not
require any parametric assumptions concerning the generator functions at the
nodes of the tree.


title:
Effective harmonic potentials: insights into the internal cooperativity
  and sequence-specificity of protein dynamics

abstract:
  The proper biological functioning of proteins often relies on the occurrence
of coordinated fluctuations around their native structure, or of wider and
sometimes highly elaborated motions. Coarse-grained elastic-network
descriptions are known to capture essential aspects of conformational dynamics
in proteins, but have so far remained mostly phenomenological, and unable to
account for the chemical specificities of amino acids. Here, we propose a
method to derive residue- and distance-specific effective harmonic potentials
from the statistical analysis of an extensive dataset of NMR conformational
ensembles. These potentials constitute dynamical counterparts to the mean-force
statistical potentials commonly used for static analyses of protein structures.
In the context of the elastic network model, they yield a strongly improved
description of the cooperative aspects of residue motions, and give the
opportunity to systematically explore the influence of sequence details on
protein dynamics.


title: Lack of controllability of thermal systems with memory

abstract:
  Heat equations with memory of Gurtin-Pipkin type have controllability
properties which strongly resemble those of the wave equation. Instead, recent
counterexamples show that when the laplacian appears also out of the memory
term, the control properties do not parallel those of the (memoryless) heat
equation, in the sense that there are $L^2$-initial conditions which cannot be
controlled to zero. The proof of this fact (presented in previous papers)
consists in the construction of two quite special examples of systems with
memory which cannot be controlled to zero. Here we prove that lack of
controllability holds in general, for every systems with smooth memory kernel.


title:
The effect of Al doping on the structure and magnetism in cobaltite
  CaBaCo4O7

abstract:
  We report the effects of Al-doping on the structure and magnetic properties
in CaBa(Co$_{1-x}$Al$_{x}$)$_4$O$_7$ (0$\leq$x$\leq$0.25). The system exhibits
a structural transition from an orthorhombic symmetry to a hexagonal symmetry
when the Al content exceeds $x =$ 0.1. The Curie temperature and the value of
the magnetization decrease with increasing Al doping level, indicating that the
ferrimagnetic ground state is gradually suppressed. The ground state eventually
transits into a spin-glass state for $x >$ 0.1. Moreover, the short-range
magnetic correlations, which occur at high temperatures in CaBaCo$_4$O$_7$, are
found to be gradually suppressed with increasing Al content and eventually
disappear for $x =$ 0.25. By comparing our results with other Co-site doping
cases, we suggest that the lattice and the spin degrees of freedom are
relatively decoupled in CaBaCo$_4$O$_7$.


title:
Substrate-Independent Catalyst-Free Synthesis of High-Purity Bi2Se3
  Nanostructures

abstract:
  We describe a catalyst-free vapor-solid synthesis of bismuth selenide
(Bi2Se3) nanostructures at ambient pressure with hydrogen as a carrier gas. The
nanostructures were synthesized on glass, silicon and mica substrates and the
method yields a variety of nanostructures: nanowires, nanoribbons,
nanoplatelets and nanoflakes. The materials analysis shows high chemical purity
in all cases, without sacrificing the crystalline structure of Bi2Se3.
Low-temperature measurements of the nanostructures indicate contributions from
the surface states with a tunable carrier density. Samples synthesized on
flexible mica substrates show no significant change in resistance upon bending,
indicating robustness of as-grown Bi2Se3 nanostructures and their suitability
for device applications.


title: Snapshots of non-equilibrium Dirac carrier distributions in graphene

abstract:
  The optical properties of graphene are made unique by the linear band
structure and the vanishing density of states at the Dirac point. It has been
proposed that even in the absence of a semiconducting bandgap, a relaxation
bottleneck at the Dirac point may allow for population inversion and lasing at
arbitrarily long wavelengths. Furthermore, efficient carrier multiplication by
impact ionization has been discussed in the context of light harvesting
applications. However, all these effects are difficult to test quantitatively
by measuring the transient optical properties alone, as these only indirectly
reflect the energy and momentum dependent carrier distributions. Here, we use
time- and angle-resolved photoemission spectroscopy with femtosecond extreme
ultra-violet (EUV) pulses at 31.5 eV photon energy to directly probe the
non-equilibrium response of Dirac electrons near the K-point of the Brillouin
zone. In lightly hole-doped epitaxial graphene samples, we explore excitation
in the mid- and near-infrared, both below and above the minimum photon energy
for direct interband transitions. While excitation in the mid-infrared results
only in heating of the equilibrium carrier distribution, interband excitations
give rise to population inversion, suggesting that terahertz lasing may be
possible. However, in neither excitation regime do we find indication for
carrier multiplication, questioning the applicability of graphene for light
harvesting. Time-resolved photoemission spectroscopy in the EUV emerges as the
technique of choice to assess the suitability of new materials for
optoelectronics, providing quantitatively accurate measurements of
non-equilibrium carriers at all energies and wavevectors.


title: On Hodges and Lehmann's "$6/\pi$ result"

abstract:
  While the asymptotic relative efficiency (ARE) of Wilcoxon rank-based tests
for location and regression with respect to their parametric Student
competitors can be arbitrarily large, Hodges and Lehmann (1961) have shown that
the ARE of the same Wilcoxon tests with respect to their van der Waerden or
normal-score counterparts is bounded from above by $6/\pi\approx 1.910$. In
this paper, we revisit that result, and investigate similar bounds for
statistics based on Student scores. We also consider the serial version of this
ARE. More precisely, we study the ARE, under various densities, of the
Spearman-Wald-Wolfowitz and Kendall rank-based autocorrelations with respect to
the van der Waerden or normal-score ones used to test (ARMA) serial dependence
alternatives.


title: Fast SVM training using approximate extreme points

abstract:
  Applications of non-linear kernel Support Vector Machines (SVMs) to large
datasets is seriously hampered by its excessive training time. We propose a
modification, called the approximate extreme points support vector machine
(AESVM), that is aimed at overcoming this burden. Our approach relies on
conducting the SVM optimization over a carefully selected subset, called the
representative set, of the training dataset. We present analytical results that
indicate the similarity of AESVM and SVM solutions. A linear time algorithm
based on convex hulls and extreme points is used to compute the representative
set in kernel space. Extensive computational experiments on nine datasets
compared AESVM to LIBSVM \citep{LIBSVM}, CVM \citep{Tsang05}, BVM
\citep{Tsang07}, LASVM \citep{Bordes05}, $\text{SVM}^{\text{perf}}$
\citep{Joachims09}, and the random features method \citep{rahimi07}. Our AESVM
implementation was found to train much faster than the other methods, while its
classification accuracy was similar to that of LIBSVM in all cases. In
particular, for a seizure detection dataset, AESVM training was almost $10^3$
times faster than LIBSVM and LASVM and more than forty times faster than CVM
and BVM. Additionally, AESVM also gave competitively fast classification times.


title: BV technique for investigating 1-D interfaces

abstract:
  To investigate the internal structure of the magnetopause with spacecraft
data, it is crucial to be able to determine its normal direction and to convert
the measured time series into spatial profiles. We propose here a new
single-spacecraft method, called the BV method, to reach these two objectives.
Its name indicates that the method uses a combination of the magnetic field (B)
and velocity (V) data. The method is tested on simulation and Cluster data, and
a short overview of the possible products is given. We discuss its assumptions
and show that it can bring a valuable improvement with respect to previous
methods.

categories: astro-ph.EP physics.geo-ph physics.plasm-ph physics.space-ph


title:
Multi-Nested Pendula: a new concept for vibration isolation and its
  application to gravitational wave detectors

abstract:
  Adequate vibration isolation is of great importance for the design of any
sensitive experiment measuring mechanical motions. The so-called multistage or
multipole mechanical low pass filter is a common artifact used for the
construction of highly effective vibration isolation. However, the problem with
it is the vertical clearance needed inside the vacuum chambers for the
construction of numerous, long pendulum stages necessary for effective
horizontal vibration isolation. The purpose of this work is to introduce a new
concept, called the multi-nested pendula concept, which solves this problem.
The attenuation performance of an ideal multistage nested pendula filter is
better than that of an ideal multistage common equal pendula filter by a factor
of N^{N}, where N is the number of stages used, making this idea of a
multi-nested pendula a very interesting one. The initial results (of stability
and system resonances) measured for a prototype reinforce the viability of the
practical implementation of such idea. A detailed study for the realization of
a cryogenic and fully operational version to be used in LIGO is going to be
done in a future study.


title: The INTEGRAL Galactic Plane Scanning

abstract:
  After the first nine years of INTEGRAL operational life, the discovery of new
sources and source types, a large fraction of which are highly transient or
highly absorbed, is certainly one of the most compelling results and legacies
of INTEGRAL. Frequent monitoring of the Galactic Plane in AO8 and AO9 campaigns
allowed us to detect transient sources, both known and new, confirming that the
gamma-ray sky is dominated by the extreme variability of different classes of
objects. Regular scans of the Galactic Plane by INTEGRAL provide the most
sensitive hard X-ray wide survey to date of our Galaxy, with flux limits of the
order of 0.3 mCrab for an exposure time of ~2Ms. Many transient sources have
been detected on a wide range of time scales (~hours to months) and identified
by triggered followup observations, mainly by Swift/XRT and optical/infrared
telescopes. These discoveries are very important to characterize the X-ray
binary population in our Galaxy, that is necessary input for evolution studies.
The transient source monitoring is crucial to sample a variety of physical
conditions corresponding to a large span in luminosity. The long exposure times
available allow us to define the spectral and timing properties of the known
sources and the global properties of each object class.