title: A lightface analysis of the differentiability rank

abstract:
  We examine the computable part of the differentiability hierarchy defined by
Kechris and Woodin. In that hierarchy, the rank of a differentiable function is
an ordinal less than omega_1 which measures how complex it is to verify
differentiability for that function. We show that for each recursive ordinal
alpha>0, the set of Turing indices of C[0,1] functions that are differentiable
with rank at most alpha is Pi_{2 alpha + 1}-complete. This result is expressed
in the notation of Ash and Knight.


title: Phase topology of one nonclassical integrable problem of dynamics

abstract:
  We consider the integrable system with three degrees of freedom for which
Sokolov and Tsiganov specified Lax representation. Lax representation
generalizes L-A pair of the Kowalevski gyrostat in two constant fields, found
by A.G.Reyman and M.A.Semenov-Tian-Shansky. In the paper, we give the explicit
formulas for the (independent almost everywhere) additional first integrals K
and G. These integrals are functionally connected with factors of a spectral
curve of L-A pair by Sokolov and Tsiganov. Due to this form of additional
integrals K and G, without constant gyrostatic moment, we managed to find
analytically two invariant four-dimensional submanifolds on which the induced
dynamic system is almost everywhere Hamiltonian system with two degrees of
freedom. System of equations that describes one of these invariant submanifolds
is a generalization of invariant relations of an integrable Bogoyavlensky case
in dynamics of a rigid body. To describe phase topology of the system as a
whole we use the method of critical subsystems. For each subsystem, we
construct the bifurcation diagrams and specify the bifurcations of Liouville
tori both in subsystems, and in the system as a whole.


title: Nanoscale Fourier-transform MRI

abstract:
  We report a method for nanometer-scale pulsed nuclear magnetic resonance
imaging and spectroscopy. Periodic radiofrequency pulses are used to create
temporal correlations in the statistical polarization of a solid organic
sample. The spin density is spatially encoded by applying a series of intense
magnetic field gradient pulses generated by focusing electric current through a
nanometer-scale metal constriction. We demonstrate this technique using a
silicon nanowire mechanical oscillator as a magnetic resonance sensor to image
1H spins in a polystyrene sample. We obtain a two-dimensional projection of the
sample proton density with approximately 10-nm resolution.


title: Phylogenetic analysis of gene expression

abstract:
  Phylogenetic analyses of gene expression have great potential for addressing
a wide range of questions. These analyses will, for example, identify genes
that have evolutionary shifts in expression that are correlated with
evolutionary changes in morphological, physiological, and developmental
characters of interest. This will provide entirely new opportunities to
identify genes related to particular phenotypes. There are, however, three key
challenges that must be addressed for such studies to realize their potential.
First, gene expression data must be measured from multiple species, some of
which may be field collected, and parameterized in such a way that they can be
compared across species. Second, it will be necessary to develop phylogenetic
comparative methods suitable for large multidimensional datasets. In most
phylogenetic comparative studies to date, the number n of independent
observations (independent contrasts) has been greater than the number p of
variables (characters). The behavior of comparative methods for these classic
n>p problems are now well understood under a wide variety of conditions. In
gene expression studies, and studies based on other high-throughput tools, the
number n of samples is dwarfed by the number p of variables. The estimated
covariance matrices will be singular, complicating their analysis and
interpretation, and prone to spurious results. Third, new approaches are needed
to investigate the expression of the many genes whose phylogenies are not
congruent with species phylogenies due to gene loss, gene duplication, and
incomplete lineage sorting. Here we outline general project design
considerations for phylogenetic analyses of gene expression, and suggest
solutions to these three categories of challenges. These topics are relevant to
high-throughput phenotypic data well beyond gene expression.


title:
Frustrated colloidal ordering and fully packed loops in arrays of
  optical traps

abstract:
  We propose that a system of colloidal particles interacting with a honeycomb
array of optical traps that each contain three wells can be used to realize a
fully packed loop model. One of the phases in this system can be mapped to
Baxter's three-coloring problem, offering an easily accessible physical
realization of this problem. As a function of temperature and interaction
strength, we find a series of phases, including long range ordered loop or
stripe states, stripes with sliding symmetries, random packed loop states, and
disordered states in which the loops break apart. Our geometry could be
constructed using ion trap arrays, BEC vortices in optical traps, or magnetic
vortices in nanostructured superconductors.


title: Nonlinear Effects in Multi-Photon Polaritonics

abstract:
  We consider theoretically nonlinear effects in a semiconductor quantum well
embedded inside a photonic microcavity. Two-photon absorption by a 2p exciton
state is considered and investigated; the matrix element of two-photon
absorption is calculated. We compute the emission spectrum of the sample and
demonstrate that under coherent pumping the nonlinearity of the two photon
absorption process gives rise to bistability.


title:
Hidden symmetries induced by a canonical transformation and gauge
  structure of compactified Yang-Mills theories

abstract:
  Compactified Yang-Mills theories with one universal extra dimension were
found [arXiv:1008.4638] to exhibit two types of gauge invariances: the standard
gauge transformations (SGTs) and the nonstandard gauge transformations (NSGTs).
In the present work we show that these transformations are not exclusive to
compactified scenarios. Introducing a notion of hidden symmetry, based on the
fundamental concept of canonical transformation, we analyse three different
gauge systems, each of which is mapped to a certain effective theory that is
invariant under the so-called SGTs and NSGTs. The systems under discussion are:
(i) four dimensional pure $SU(3)$ Yang-Mills theory, (ii) four dimensional
$SU(3)$ Yang-Mills with spontaneous symmetry breaking, and (iii) pure
Yang-Mills theory with one universal compact extra dimension. The canonical
transformation, that induces the notion of hidden symmetry, maps objects with
well defined transformation laws under a gauge group $G$ to well defined
objects under a non-trivial subgroup $H \subset G$. In the case where
spontaneous symmetry breaking is present, the set of SGTs corresponds to the
group into which the original gauge group is broken into, whereas the NSGTs are
associated to the broken generators and can be used to define the unitary
gauge. For the system (iii), the SGTs coincide with the gauge group $
SU(N,\cal{M}^{4}) $, whereas the NSGTs do not form a group; in this system the
'fundamental' theory and the effective one are shown to be classically
equivalent.


title: Toward motivic integration over wild Deligne-Mumford stacks

abstract:
  We discuss how the motivic integration will be generalized to wild
Deligne-Mumford stacks, that is, stabilizers may have order divisible by the
characteristic of the base or residue field. We pose several conjectures on
this topic. We also present some possible applications concerning stringy
invariants, resolution of singularities, and weighted counts of extensions of
local fields.


title:
PESSTO monitoring of SN 2012hn: further heterogeneity among faint type I
  supernovae

abstract:
  We present optical and infrared monitoring data of SN 2012hn collected by the
Public ESO Spectroscopic Survey for Transient Objects (PESSTO). We show that SN
2012hn has a faint peak magnitude (MR ~ -15.7) and shows no hydrogen and no
clear evidence for helium in its spectral evolution. Instead, we detect
prominent Ca II lines at all epochs, which relates this transient to previously
described 'Ca-rich' or 'gap' transients. However, the photospheric spectra
(from -3 to +32 d with respect to peak) of SN 2012hn show a series of
absorption lines which are unique, and a red continuum that is likely intrinsic
rather than due to extinction. Lines of Ti II and Cr II are visible. This may
be a temperature effect, which could also explain the red photospheric colour.
A nebular spectrum at +150d shows prominent CaII, OI, CI and possibly MgI lines
which appear similar in strength to those displayed by core-collapse SNe. To
add to the puzzle, SN 2012hn is located at a projected distance of 6 kpc from
an E/S0 host and is not close to any obvious starforming region. Overall SN
2012hn resembles a group of faint H-poor SNe that have been discovered recently
and for which a convincing and consistent physical explanation is still
missing. They all appear to explode preferentially in remote locations offset
from a massive host galaxy with deep limits on any dwarf host galaxies,
favouring old progenitor systems. SN 2012hn adds heterogeneity to this sample
of objects. We discuss potential explosion channels including He-shell
detonations and double detonations of white dwarfs as well as peculiar
core-collapse SNe.


title:
Generalized Entropy and Global Quantum Discord in Multi-party Quantum
  systems

abstract:
  Using Tsallis-q entropy, we introduce the generalized concept of global
quantum discord, namely the q-global quantum discord, and provide its analytic
evaluation for two classes of multi-qubit states. We also provide a sufficient
condition, for which the pairwise quantum correlations in terms of q-global
quantum discord is monogamous in multi-party quantum systems.


title: Foams and sl(n) cohomology for tangles (n > 3)

abstract:
  We use 4-valent planar graphs and singular cobordisms (called foams) to
construct an integral doubly-graded cohomology for tangles, and in particular
for links, whose graded Euler characteristic yields the sl(n) link polynomial
(for n > 3).


title: Totally Silver Graphs

abstract:
  A totally silver coloring of a graph G is a k--coloring of G such that for
every vertex v \in V(G), each color appears exactly once on N[v], the closed
neighborhood of v. A totally silver graph is a graph which admits a totally
silver coloring. Totally silver coloring are directly related to other areas of
graph theory such as distance coloring and domination. In this work, we present
several constructive characterizations of totally silver graphs and bipartite
totally silver graphs. We give several infinite families of totally silver
graphs. We also give cubic totally silver graphs of girth up to 10.


title: Structure and Flow of the Nucleon Eigenstates in Lattice QCD

abstract:
  A determination of the excited energy eigenstates of the nucleon,
$s=c{1}{2}$, $I={1}{2}$, $N^{\pm}$, is presented in full QCD using 2+1 flavor
PACS-CS gauge configurations. The correlation-matrix method is used and is
built using standard nucleon interpolators employing smearings at the fermion
sources and sinks. We develop and demonstrate a new technique that allows the
eigenvectors obtained to be utilized to track the propagation of the intrinsic
nature of energy-states from one quark mass to the next. This approach is
particularly useful for larger dimension correlation matrices where more
near-degenerate energy-states can appear in the spectrum.


title:
Inverse cascade behavior in freely decaying two-dimensional fluid
  turbulence

abstract:
  We present results from an ensemble of 50 runs of two-dimensional
hydrodynamic turbulence with spatial resolution of 2048^2 grid points, and from
an ensemble of 10 runs with 4096^2 grid points. All runs in each ensemble have
random initial conditions with same initial integral scale, energy, enstrophy,
and Reynolds number. When both ensemble- and time-averaged, inverse energy
cascade behavior is observed, even in the absence of external mechanical
forcing: the energy spectrum at scales larger than the characteristic scale of
the flow follows a k^(-5/3) law, with negative flux, together with a k^(-3) law
at smaller scales, and a positive flux of enstrophy. The source of energy for
this behavior comes from the modal energy around the energy containing scale at
t=0. The results shed some light into connections between decaying and forced
turbulence, and into recent controversies in experimental studies of
two-dimensional and magnetohydrodynamic turbulent flows.

categories: physics.flu-dyn nlin.AO physics.ao-ph physics.space-ph


title: Electron-phonon coupling in DyFeO3 revealed by infrared spectroscopy

abstract:
  We have investigated crystal field and phonon dynamics of the multiferroic
orthoferrite DyFeO$_3$ via polarized infrared spectroscopy. Reflectance of
single crystals was measured in the far- to mid-infrared spectral range at
range of temperatures from 10-295 K. We observe a strongly anisotropic phonon
spectrum which differs from earlier lattice dynamical calculations in its
symmetry, as well as a mode with significant and unusual temperature dependence
that we interpret as a coupled phonon-crystal-field excitation.


title:
Experimental demonstration of free-space information transfer using
  phase modulated orbital angular momentum radio

abstract:
  In a series of fundamental proof-of-principle experiments, comprising
numerical, controlled laboratory, and real-world experimentation, we have shown
that it is possible to use the angular momentum physical layer for radio
science and radio communication applications. Here we report a major, decisive
step toward the realization of the latter, in the form of the real-world
experimental demonstration that a radio beam carrying orbital angular momentum
(OAM) can readily be digitally phase shift modulated and that the information
thus encoded can be effectively transferred in free space to a remote receiver.
The experiment was carried out in an urban setting and showed that the
information transfer is robust against ground reflections and interfering radio
signals. The importance of our results lies in the fact that digital phase
shift keying (PSK) protocols are used in many present-day wireless
communication scenarios, allowing new angular momentum radio implementations to
use methods and protocols that are backward compatible with existing linear
momentum ones.

categories: physics.class-ph astro-ph.IM physics.optics physics.space-ph


title: Torsion pairs and filtrations in abelian categories with tilting objects

abstract:
  Given a noetherian abelian category $\mathcal Z$ of homological dimension two
with a tilting object $T$, the abelian category $\mathcal Z$ and the abelian
category of modules over $\text{End} (T)^{\textit{op}}$ are related by a
sequence of two tilts; we give an explicit description of the torsion pairs
involved. We then use our techniques to obtain a simplified proof of a theorem
of Jensen-Madsen-Su, that $\mathcal Z$ has a three-step filtration by
extension-closed subcategories. Finally, we generalise Jensen-Madsen-Su's
filtration to a noetherian abelian category of any finite homological
dimension.


title: Hypersurfaces with constant anisotropic mean curvatures

abstract:
  We apply the evolution method to present a new proof of the Alexandrov type
theorem for constant anisotropic mean curvature hypersurfaces in the Euclidean
space $\mathbb{R}^{n+1}$.


title:
Inverse energy cascade and emergence of large coherent vortices in
  turbulence driven by Faraday waves

abstract:
  We report the generation of large coherent vortices via inverse energy
cascade in Faraday wave driven turbulence. The motion of floaters in the
Faraday waves is three dimensional but its horizontal velocity fluctuations
show unexpected similarity with two-dimensional turbulence. The inverse cascade
is detected by measuring frequency spectra of the Lagrangian velocity, and it
is confirmed by computing the third moment of the horizontal velocity
fluctuations. This is observed in deep water in a broad range of wavelengths.
The results broaden the scope of recent findings on Faraday waves in thin
layers [A. von Kameke, \textit{et al.}, \textit{Phys. Rev. Lett.} \textbf{107},
074502 (2011)].


title: Equivalence of Two Proof Techniques for Non-Shannon-type Inequalities

abstract:
  We compare two different techniques for proving non-Shannon-type information
inequalities. The first one is the original Zhang-Yeung's method, commonly
referred to as the copy/pasting lemma/trick. The copy lemma was used to derive
the first conditional and unconditional non-Shannon-type inequalities. The
second technique first appeared in Makarychev et al paper [7] and is based on a
coding lemma from Ahlswede and K\"orner works. We first emphasize the
importance of balanced inequalities and provide a simpler proof of a theorem of
Chan's for the case of Shannon-type inequalities. We compare the power of
various proof systems based on a single technique.


title: On the power spectrum generated during inflation

abstract:
  Recently there have been differing viewpoints on how to evaluate the
curvature power spectrum generated during inflation. Since the primordial
curvature power spectrum is the seed for structure formation and provides a
link between observations and inflationary parameters, it is important to
resolve any disagreements over the expression for the power spectrum. In this
article we discuss these differing viewpoints and indicate issues that are
relevant to both approaches. We then argue why the standard expression is
valid.


title:
Antifferomagnetic FeSe monolayer on SiTiO$_{3}$: The charge doping and
  electric field effects

abstract:
  We present theoretically the electronic structure of antiferromagnetic (AFM)
FeSe monolayer on TiO$_{2}$ terminated SrTiO$_{3}$(001) surface. It is revealed
that the striking disappearance of the Fermi surface around the Brillouin zone
(BZ) center can be well explained by the antiferromatnetic (AFM) phase. We show
that the system has a considerable charge transfer from SrTiO$_{3}$(001)
substrate to FeSe monolayer, and so has a self-constructed electric field. The
FeSe monolayer band structure near the BZ center is sensitive to charge doping,
and the spin-resolved energy bands at BZ corner are distorted to be flattened
by the perpendicular electric field. We propose a tight-binding model
Hamiltonian to take these key factors into account. We also show that this
composite structure is an ideal electron-hole bilayer system, with electrons
and holes respectively formed in FeSe monolayer and TiO$_{2}$ surface layer.


title: Unsteady Reversed Stagnation-Point Flow over a Flat Plate

abstract:
  This paper investigates the nature of the development of two-dimensional
laminar flow of an incompressible fluid at the reversed stagnation-point. ". In
this study, we revisit the problem of reversed stagnation-point flow over a
flat plate. Proudman and Johnson (1962) first studied the flow and obtained an
asymptotic solution by neglecting the viscous terms. This is no true in
neglecting the viscous terms within the total flow field. In particular it is
pointed out that for a plate impulsively accelerated from rest to a constant
velocity V0 that a similarity solution to the self-similar ODE is obtained
which is noteworthy completely analytical.


title:
Fractional quantum Hall effect of topological surface states under a
  strong tilted magnetic field

abstract:
  The fractional quantum Hall effect (FQHE) of topological surface-state
particles under a tilted strong magnetic field is theoretically studied by
using the exact diagonalization method. The Haldane's pseudopotentials for the
Coulomb interaction are analytically obtained. The results show that by
increasing the in-plane component of the tilted magnetic field, the FQHE state
at $n$=0 Landau level (LL) becomes more stable, while the stabilities of
$n$=$\pm1$ LLs become weaker. Moreover, we find that the excitation gaps of the
$\nu=1/3$ FQHE states increase as the tilt angle is increased.


title:
The effect of the warping term on the fractional quantum Hall states in
  topological insulators

abstract:
  The warping effect on the fractional quantum Hall (FQH) states in topological
insulators is studied theoretically. Based on the perturbed wavefunctions,
which include contributions from the warping term, analytical expressions for
Haldane's pseudopotentials are obtained. We show that the warping term does not
break the symmetry of the pseudopotentials for $n$=$\pm1$ Landau levels (LLs).
With increasing the warping strength of the Fermi surface, our results indicate
that the stability of the FQH states for LL $n=0$ (LLs $n$=$\pm1$) becomes
stronger (weaker), and the excitation gap at $\nu=1/3$ FQH state for LL $n$=0
also increases while the gaps for LLs $n$=$\pm1$ are unchanged.


title: Alpha-diversity processes and normalized inverse-Gaussian diffusions

abstract:
  The infinitely-many-neutral-alleles model has recently been extended to a
class of diffusion processes associated with Gibbs partitions of two-parameter
Poisson-Dirichlet type. This paper introduces a family of infinite-dimensional
diffusions associated with a different subclass of Gibbs partitions, induced by
normalized inverse-Gaussian random probability measures. Such diffusions
describe the evolution of the frequencies of infinitely-many types together
with the dynamics of the time-varying mutation rate, which is driven by an
alpha-diversity diffusion. Constructed as a dynamic version, relative to this
framework, of the corresponding notion for Gibbs partitions, the latter is
explicitly derived from an underlying population model and shown to coincide,
in a special case, with the diffusion approximation of a critical Galton-Watson
branching process. The class of infinite-dimensional processes is characterized
in terms of its infinitesimal generator on an appropriate domain, and shown to
be the limit in distribution of a certain sequence of Feller diffusions with
finitely-many types. Moreover, a discrete representation is provided by means
of appropriately transformed Moran-type particle processes, where the particles
are samples from a normalized inverse-Gaussian random probability measure. The
relationship between the limit diffusion and the two-parameter model is also
discussed.


title: A Modern Approach to the Efficient-Market Hypothesis

abstract:
  Market efficiency at least requires the absence of weak arbitrage
opportunities, but this is not sufficient to establish a situation where the
market is sensitive, i.e., where it "fully reflects" or "rapidly adjusts to"
some information flow including the evolution of asset prices. By contrast, No
Weak Arbitrage together with market sensitivity is sufficient and necessary for
a market to be informationally efficient.


title:
First-principles study of temperature-dependent diffusion coefficients:
  Hydrogen, deuterium, and tritium in $\alpha$-Ti

abstract:
  We report the prediction of temperature-dependent diffusion coefficients of
interstitial hydrogen, deuterium, and tritium atoms in $\alpha$-Ti using
transition state theory. The microscopic parameters in the pre-factor and
activation energy of the impurity diffusion coefficients are obtained from
first-principles total energy and phonon calculations including the full
coupling between the vibrational modes of the diffusing atom with the host
lattice. The dual occupancy case of impurity atom in the hcp matrix are
considered, and four diffusion paths are combined to obtain the final diffusion
coefficients. The calculated diffusion parameters show good agreement with
experiments. Our numerical results indicate that the diffusions of deuterium
and tritium atoms are slower than that of the hydrogen atom at temperatures
above 425 K and 390 K, respectively.


title:
Optical-Near Infrared Color Gradients And Merging History Of Elliptical
  Galaxies

abstract:
  It has been suggested that merging plays an important role in the formation
and the evolution of elliptical galaxies(EGs). In order to understand the past
merging history of EGs, we studied the optical-NIR color gradients of 204 EGs.
The use of the optical and the NIR data provides large wavelength baselines,
and breaks the age-metallicity(Z) degeneracy, allowing us to derive age and Z
gradients. The use of the deep SDSS Stripe 82 images make it possible for us to
examine how the color/age/Z gradients are related to merging features. We find
that the optical-NIR color and the age/Z gradients of EGs with tidal features
are consistent with those of relaxed EGs suggesting that the two populations
underwent a similar merging history on average and that mixing of stars was
more or less completed before the tidal features disappear. EGs with dust
features have steeper color gradients than the other two types, even after
masking out dust features during the analysis, which can be due to a process
involving wet merging. More importantly, we find that the scatter in the
color/age/Z gradients of the relaxed and merging feature types, decreases as
their luminosities increase at M > 10^{11.4} M_{\odot} but stays to be large at
lower luminosities. Mean Z gradients appear nearly constant over the explored
mass range, but a possible flattening is observed at the massive end. According
to our toy model that predicts how the distribution of Z gradients changes as a
result of major dry merging, the mean Z gradient should flatten by 40% and its
scatter become smaller by 80% per a mass doubling scale if EGs evolve only
through major dry merger. Our result, although limited by a number statistics
at the massive end, is consistent with the picture that major dry merging is an
important mechanism for the evolution for EGs at M > 10^{11.4} M_{\odot}, but
less important at the lower mass range.


title:
Coulomb breakup reactions of $^{11}$Li in the coupled-channel
  $^9$Li~+~$n$~+~$n$ three-body model

abstract:
  We investigate the three-body Coulomb breakup of a two-neutron halo nucleus
$^{11}$Li. We use the coupled-channel $^9$Li + $n$ + $n$ three-body model,
which includes the coupling between last neutron states and the various
$2p$-$2h$ configurations in $^9$Li due to the tensor and pairing correlations.
The three-body scattering states of $^{11}$Li are described by using the
combined methods of the complex scaling and the Lippmann-Schwinger equation.
The calculated breakup cross section successfully reproduces the experiments.
The large mixing of the s-state in the halo ground state of $^{11}$Li is shown
to play an important role in explanation of shape and strength of the breakup
cross section. In addition, we predict the invariant mass spectra for binary
subsystems of $^{11}$Li. It is found that the two kinds of virtual s-states of
$^9$Li-$n$ and $n$-$n$ systems in the final three-body states of $^{11}$Li
largely contribute to make low-lying peaks in the invariant mass spectra. On
the other hand, in the present analysis, it is suggested that the contributions
of the p-wave resonances of $^{10}$Li is hardly confirmed in the spectra.


title: Entanglement of Tripartite States with Decoherence in Noninertial frames

abstract:
  The one-tangle and {\pi}-tangle are used to quantify the entanglement of a
tripartite GHZ state in noninertial frames when the system interacts with a
noisy environment in the form of phase damping, phase flip and bit flip
channel. It is shown that the two-tangles behave as a closed system. The
one-tangle and {\pi}-tangle have different behaviors in the three channel. In
the case of phase damping channel, depending on the kind of coupling, the
sudden death of both one-tangle and {\pi}-tangle may or may not happen. Whereas
in the case of phase flip channel the sudden death cannot be avoided. The
effect of decoherence may be ignored in the limit of infinite acceleration when
the system interacts with a bit flip channel. Furthermore, a sudden rebirth of
the one-tangle and {\pi}-tangle occur in the case of phase flip channel that
may be delayed when collective coupling is switched on.


title: Staffing many-server systems with admission control and retrials

abstract:
  In many-server systems it is crucial to staff the right number of servers so
that targeted service levels are met. These staffing problems typically lead to
constraint satisfaction problems that are hard to solve. During the last
decade, a powerful many-server asymptotic theory has been developed to solve
such problems and optimal staffing rules are known to obey the square-root
staffing principle. This paper develops many-server asymptotics in the
so-called QED regime, and presents refinements to many-server asymptotics and
square-root staffing for a Markovian queueing model with admission control and
retrials.


title:
First passage times to congested states of many-server systems in the
  Halfin-Whitt regime

abstract:
  We consider the heavy-traffic approximation to the $GI/M/s$ queueing system
in the Halfin-Whitt regime, where both the number of servers $s$ and the
arrival rate $\lambda$ grow large (taking the service rate as unity), with
$\lambda=s-\beta\sqrt{s}$ and $\beta$ some constant. In this asymptotic regime,
the queue length process can be approximated by a diffusion process that
behaves like a Brownian motion with drift above zero and like an
Ornstein-Uhlenbeck process below zero. We analyze the first passage times of
this hybrid diffusion process to levels in the state space that represent
congested states in the original queueing system.


title: Cooperative Boolean systems with generically long attractors I

abstract:
  We study the class of cooperative Boolean networks whose only regulatory
functions are COPY, binary AND, and binary OR. We prove that for all
sufficiently large N and c < 2 there exist Boolean networks in this class that
have an attractor of length > c^N whose basin of attraction comprises an
arbitrarily large fraction of the state space. The existence of such networks
contrasts with results on various other types of dynamical systems that show
nongenericity or absence of non-steady state attractors under the assumption of
cooperativity.


title: Excited Young diagrams, equivariant K-theory, and Schubert varieties

abstract:
  We give combinatorial descriptions of the restrictions to T-fixed points of
the classes of structure sheaves of Schubert varieties in the T-equivariant
K-theory of Grassmannians and of maximal isotropic Grassmannians of orthogonal
and symplectic types. We also give formulas, based on these descriptions, for
the Hilbert series and Hilbert polynomials at T-fixed points of the
corresponding Schubert varieties. These descriptions and formulas are given in
terms of two equivalent combinatorial models: excited Young diagrams and
set-valued tableaux. The restriction fomulas are positive, in that for a
Schubert variety of codimension d, the formula equals (-1)^d times a sum, with
nonnegative coefficients, of monomials in the expressions (e^{-\alpha}-1), as
\alpha runs over the positive roots. In types A_n and C_n the restriction
formulas had been proved earlier by [Kreiman 05], [Kreiman 06] by a different
method. In type A_n, the formula for the Hilbert series had been proved earlier
by [Li-Yong 12]. The method of this paper, which relies on a restriction
formula of [Graham 02] and [Willems 06], is based on the method used by
[Ikeda-Naruse 09] to obtain the analogous formulas in equivariant cohomology.
The formulas we give differ from the K-theoretic restriction formulas given by
[Ikeda-Naruse 11], which use different versions of excited Young diagrams and
set-valued tableaux. We also give Hilbert series and Hilbert polynomial
formulas which are valid for Schubert varieties in any cominuscule flag
variety, in terms of the 0-Hecke algebra.


title:
Tailoring the electronic properties of SrRuO3 films in SrRuO3/LaAlO3
  superlattices

abstract:
  The electronic properties of SrRuO3/LaAlO3 (SRO/LAO) superlattices with
different interlayer thicknesses of SRO layers were studied. As the thickness
of SRO layers is reduced, the superlattices exhibit a metal-insulator
transition implying transformation into a more localized state from its
original bulk metallic state. The strain effect on the metal-insulator
transition was also examined. The origin of the metal-insulator transition in
ultrathin SRO film is discussed. All the superlattices, even those with SRO
layers as thin as 2 unit cells, are ferromagnetic at low temperatures.
Moreover, we demonstrate field effect devices based on such multilayer
superlattice structures.


title: Heat engine driven by purely quantum information

abstract:
  The key question of this paper is whether work can be extracted from a heat
engine by using purely quantum mechanical information. If the answer is yes,
what is its mathematical formula? First, by using a bipartite memory we show
that the work extractable from a heat engine is bounded not only by the free
energy change and the sum of the entropy change of an individual memory but
also by the change of quantum mutual information contained inside the memory.
We then find that the engine can be driven by purely quantum information,
expressed as the so-called quantum discord, forming a part of the quantum
mutual information. To confirm it, as a physical example we present the Szilard
engine containing a diatomic molecule with a semi-permeable wall.


title: Standard Young Tableaux and Colored Motzkin Paths

abstract:
  In this paper, we propose a notion of colored Motzkin paths and establish a
bijection between the $n$-cell standard Young tableaux (SYT) of bounded height
and the colored Motzkin paths of length $n$. This result not only gives a
lattice path interpretation of the standard Young tableaux but also reveals an
unexpected intrinsic relation between the set of SYTs with at most $2d+1$ rows
and the set of SYTs with at most 2d rows.


title:
Modelling narrow-line regions of active galaxies in the Sloan Digital
  Sky Survey - I.Sample selection and physical conditions

abstract:
  We systematically determine the electron density and electron temperature of
active galaxies and star-forming galaxies using spectroscopy from the SDSS DR7,
while mainly focusing on the NLRs. Density and temperature are determined
through the I[S II] 6716/6731 and I[O III] 5007/4363 ratios, respectively, in
our [O III] 4363 emission sample of 15 019 galaxies. We find two sequences and
the typical range of density in the NLRs of AGNs is 100-1000 /cm3. The
temperatures in the NLRs range from 10 000 to 20 000 K for Seyferts, and the
ranges were even higher and wider for LINERs and composites. We also propose
that Y_LINER ~ Y_Seyfert > Y_composite > Y_star-forming, where Y is the
characteristic present-day star-formation time-scale. While in the AGN case, we
find several strong lines of evidence suggest that some supplementary energy
source(s) should be responsible for high ionization potential.


title: Transport through a disordered topological-metal strip

abstract:
  Features of a topological phase, and edge states in particular, may be
obscured by overlapping in energy with a trivial conduction band. The
topological nature of such a conductor, however, is revealed in its transport
properties, especially in the presence of disorder. In this work, we explore
the conductance behavior of such a system with disorder present, and contrast
it with the quantized conductance in an ideal 2D topological insulator. Our
analysis relies on numerics on a lattice system and analytics on a simple toy
model. Interestingly, we find that as disorder is increased from zero, the edge
conductivity initially falls from its quantized value; yet as disorder
continues to increase, the conductivity recovers, and saturates at a value
slightly below the quantized value of the clean system. We discuss how this
effect can be understood from the tendency of the bulk states to localize,
while the edge states remain delocalized.


title:
Absence of an intrinsic value for the surface recombination velocity in
  doped semiconductors

abstract:
  A self-consistent expression for the surface recombination velocity $S$ and
the surface Fermi level unpinning energy as a function of light excitation
power ($P$) is presented for n- and p-type semiconductors doped above the
10$^{16}$ cm$^{-3}$ range. Measurements of $S$ on p-type GaAs films using a
novel polarized microluminescence technique are used to illustrate two limiting
cases of the model. For a naturally oxidized surface $S$ is described by a
power law in $P$ whereas for a passivated surface $S^{-1}$ varies
logarithmically with $P$. Furthermore, the variation in $S$ with surface state
density and bulk doping level is found to be the result of Fermi level
unpinning rather than a change in the intrinsic surface recombination velocity.
It is concluded that $S$ depends on $P$ throughout the experimentally
accessible range of excitation powers and therefore that no instrinsic value
can be determined. Previously reported values of $S$ on a range of
semiconducting materials are thus only valid for a specific excitation power.


title: Electrochemical response of biased nanoelectrodes in solution

abstract:
  Novel approaches to DNA sequencing and detection require the measurement of
electrical currents between metal probes immersed in ionic solution. Here, we
experimentally demonstrate that these systems maintain large background
currents with a transient response that decays very slowly in time and noise
that increases with ionic concentration. Using a non-equilibrium stochastic
model, we obtain an analytical expression for the ionic current that shows
these results are due to a fast electrochemical reaction at the electrode
surface followed by the slow formation of a diffusion layer. During the latter,
ions translocate in the weak electric field generated after the initial rapid
screening of the strong fields near the electrode surfaces. Our theoretical
results are in very good agreement with experimental findings.


title:
Disappearance of Nodal Gap across the Insulator-Superconductor
  Transition in a Copper-Oxide Superconductor

abstract:
  The parent compound of the copper-oxide high temperature superconductors is a
Mott insulator. Superconductivity is realized by doping an appropriate amount
of charge carriers. How a Mott insulator transforms into a superconductor is
crucial in understanding the unusual physical properties of high temperature
superconductors and the superconductivity mechanism. Here we report high
resolution angle-resolved photoemission measurement on heavily underdoped
Bi2Sr2-xLaxCuO6+d system. The electronic structure of the lightly-doped samples
exhibit a number of characteristics: existence of an energy gap along the nodal
direction, d-wave-like anisotropic energy gap along the underlying Fermi
surface, and coexistence of a coherence peak and a broad hump in the
photoemission spectra. Our results reveal a clear insulator-superconductor
transition at a critical doping level of ~0.10 where the nodal energy gap
approaches zero, the three-dimensional antiferromagnetic order disappears, and
superconductivity starts to emerge. These observations clearly signal a close
connection between the nodal gap, antiferromagnetism and superconductivity.


title:
Deciphering the ionized gas content in the massive star forming complex
  G75.78+0.34

abstract:
  We present sub-arcsecond observations toward the massive star forming region
G75.78+0.34. We used the Very Large Array to study the centimeter continuum and
H2O and CH3OH maser emission, and the Owens Valley Radio Observatory and
Submillimeter Array to study the millimeter continuum and recombination lines
(H40alpha and H30alpha). We found radio continuum emission at all wavelengths,
coming from three components: (1) a cometary ultracompact (UC) HII region with
an electron density 3.7x10^4 cm^{-3}, excited by a B0 type star, and with no
associated dust emission; (2) an almost unresolved UCHII region (EAST), located
6 arcsec to the east of the cometary UCHII region, with an electron density
1.3x10^5 cm^{-3}, and associated with a compact dust clump detected at
millimeter and mid-infrared wavelengths; and (3) a compact source (CORE),
located 2 arcsec to the southwest of the cometary arc, with a flux density
increasing with frequency, and embedded in a dust condensation of 30 Msun. The
CORE source is resolved into two compact and unresolved sources which can be
well-fit by two homogeneous hypercompact HII regions each one photo-ionized by
a B0.5 ZAMS star, or by free-free radiation from shock-ionized gas resulting
from the interaction of a jet/outflow system with the surrounding environment.
The spatial distribution and kinematics of water masers close to the CORE-N and
S sources, together with excess emission at 4.5 mum and the detected dust
emission, suggest that the CORE source is a massive protostar driving a
jet/outflow.


title:
Statistics of the structure components in S0s: implications for bar
  induced secular evolution

abstract:
  The fractions and dimension of bars, rings and lenses are studied in the
Near-IR S0 galaxy Survey (NIRS0S). We find evidence that multiple lenses in
some barred S0s are related to bar resonances in a similar manner as the inner
and outer rings, for which the outer/inner length ratio 2. Inner lenses in the
non-barred galaxies normalized to galaxy diameter are clearly smaller than
those in the barred systems. Interestingly, these small lenses in the
non-barred galaxies have similar sizes as barlenses (lens-like structures
embedded in a bar), and therefore might actually be barlenses in former barred
galaxies, in which the outer, more elongated bar component, has been destroyed.
We also find that fully developed inner lenses are on average a factor 1.3
larger than bars, whereas inner rings have similar sizes as bars. The fraction
of inner lenses is found to be constant in all family classes (A, AB, B).
Nuclear bars appear most frequently among the weakly barred (AB) galaxies,
which is consistent with the theoretical models by Maciejewski & Athanassoula
(2008). Similar sized bars as the nuclear bars were detected in seven
'non-barred' S0s. Galaxy luminosity does not uniquely define the sizes of bars
or bar-related structures, neither is there any upper limit in galaxy
luminosity for bar formation. Although all the family classes cover the same
range of galaxy luminosity, the non-barred (A) galaxies are on average 0.6 mag
brighter than the strongly barred (B) systems. Overall, our results are
consistent with the idea that bars play an important role in the formation of
the structure components of galaxies. The fact that multiple lenses are common
in S0s, and that at least the inner lenses can have very old stellar
populations, implies that the last destructive merger, or major gas accretion
event, must have taken place at a fairly high redshift.


title:
Output Filter Aware Optimization of the Noise Shaping Properties of
  {\Delta}{\Sigma} Modulators via Semi-Definite Programming

abstract:
  The Noise Transfer Function (NTF) of {\Delta}{\Sigma} modulators is typically
designed after the features of the input signal. We suggest that in many
applications, and notably those involving D/D and D/A conversion or actuation,
the NTF should instead be shaped after the properties of the
output/reconstruction filter. To this aim, we propose a framework for optimal
design based on the Kalman-Yakubovich-Popov (KYP) lemma and semi-definite
programming. Some examples illustrate how in practical cases the proposed
strategy can outperform more standard approaches.


title:
An outlook on event rates of induced earth quakes in the Netherlands: a
  preliminary analysis

abstract:
  The increasing rate in earth quakes in the Netherlands is attributed to the
enhanced depletion of Groningen natural gas, currently at a rate of 50 billion
m3 per year. We performed a model-independent analysis of the earth quake event
counts in KNMI data. We find an exponential growth since 2001 with a standard
deviation of 0.37% and a doubling time of 6.2 years, giving rise to one event
per day in 2025. A trend in the magnitude of the quakes is indiscernible. There
is no apparent sensisitivity to NAM pruduction of natural gas, which increased
linearly with a standard deviation of 9.4% over the last decade. We identify
the earth quakes with an avalanche triggered by a pressure drop, currently 50%
away from the equilibrium pressure at the depth of 3 km. Re-establishing
pressure equilibrium will proceed with an anticipated drop in soil surface up
to a few meters.


title:
Characterising the Anisotropic Mechanical Properties of Excised Human
  Skin

abstract:
  The mechanical properties of skin are important for a number of applications
including surgery, dermatology, impact biomechanics and forensic science. In
this study we have investigated the influence of location and orientation on
the deformation characteristics of 56 samples of excised human skin. Uniaxial
tensile tests were carried out at a strain rate of 0.012s$^{-1}$ on skin from
the back. Digital Image Correlation was used for 2D strain measurement and a
histological examination of the dermis was also performed. The mean ultimate
tensile strength (UTS) was 21.6$\pm$8.4MPa, the mean failure strain 54$\pm$17%,
the mean initial slope 1.18$\pm$0.88MPa, the mean elastic modulus
83.3$\pm$34.9MPa and the mean strain energy was 3.6$\pm$1.6MJ/m$^3$. A
multivariate analysis of variance has shown that these mechanical properties of
skin are dependent upon the orientation of Langer lines (P$<$0.0001-P=0.046).
The location of specimens on the back was also found to have a significant
effect on the UTS (P =0.0002), the elastic modulus (P=0.001) and the strain
energy (P=0.0052). The histological investigation concluded that there is a
definite correlation between the orientation of Langer Lines and the preferred
orientation of collagen fibres in the dermis (P$<$0.001). The data obtained in
this study will provide essential information for those wishing to model the
skin using a structural constitutive model.

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


title: Ligand field parameters and the ground state of Fe(II) phthalocyanine

abstract:
  A judicious analysis of previously published experimental data leads one to
conclude that the ground state of iron(II) phthalocyanine is an orbitally
degenerate spin triplet $a_{1g}^2 e_g^{\uparrow\downarrow\uparrow}
b_{2g}^{\uparrow}$ ($^3E_g$). The ligand field parameters, in relation to
Racah's $C$, are approximately as follows: $B_{20}/C=0.84$, $B_{40}/C=0.0074$.
The uniqueness of this result is demonstrated by means of a special diagram in
the $B_{20}/C-B_{40}/C$ plane (under additional conditions that
$B_{44}/B_{40}=35/3$ and $B/C=0.227$). The system is in a strong-ligand-field
regime, which enables the use of single-determinant techniques corrected for
correlations within the 3d shell of Fe.


title: A construction of almost automorphic minimal sets

abstract:
  We describe a general procedure to construct topological extensions of given
skew product maps with one-dimensional fibres, by blowing up a countable number
of single points to vertical segments. This allows to produce various examples
of unusual dynamics, including almost automorphic minimal sets of almost
periodically forced systems, point-distal but non-distal homeomorpisms of the
torus (as first constructed by Rees) or minimal sets of quasiperiodically
forced interval maps which are not filled-in.


title: A new solution of the star-triangle relation

abstract:
  We obtain a new solution to the star-triangle relation for an Ising-type
model with two kinds of spin variables at each lattice site, taking continuous
real values and arbitrary integer values, respectively. The Boltzmann weights
are manifestly real and positive. They are expressed through the Euler gamma
function and depend on sums and differences of spins at the ends of the edge.

categories: math-ph cond-mat.stat-mech hep-th math.MP


title:
On the multilinear Bohnenblust--Hille constants: complex versus real
  case

abstract:
  The results of this note arise a rupture between the behavior of the real and
complex best known constants for the multilinear Bohnenblust--Hille inequality;
in one side, for real scalars, we show that new upper bounds for the real
Bohnenblust--Hille inequality (the best up to now) can be obtained via a
somewhat "chaotic" combinatorial approach, while in the complex case the
combinatorial approach giving the best known constants seems to be fully
controlled. We believe that the understanding of this fact is a challenging
problem that may shed some new light to the subject. As a byproduct of our
results we present new estimates for the constants of the Bohnenblust--Hille
inequality as well as new closed formulas.


title: To what extent should we find the chiral end point?

abstract:
  We analyze the critical phenomena in the theory of strong interactions at
high temperatures starting from first principles. The model is based on the
dual Yang-Mills theory with scalar degrees of freedom - the dilatons. The
latter are produced due to the spontaneous breaking of an approximate scale
symmetry. The phase transitions are considered in systems where the field
conjugate to the order parameter has the (critical) chiral end mode. The hiral
end point (ChEP) is a distinct singular feature existence of which is dictated
by the chiral dynamics. The physical approach the effective ChEP is studied via
the influence fluctuations of two-body Bose-Einstein correlation function for
observed particles to which the chiral end mode couples.


title:
Complex Langevin dynamics and other approaches at finite chemical
  potential

abstract:
  I review the presence of the sign problem in lattice QCD at nonzero baryon
density and its relation with the overlap and Silver Blaze problems. I then
discuss progress in some cases where the sign problem can be handled, either
because the sign problem is absent or because it is milder than in full QCD.
Some time is spent on effective three-dimensional models, which can be treated
with a variety of methods. I conclude with a discussion of the applicability of
complex Langevin dynamics at nonzero density.


title:
Gaps in the HD169142 protoplanetary disk revealed by polarimetric
  imaging: Signs of ongoing planet formation?

abstract:
  We present H-band VLT/NACO polarized light images of the Herbig Ae/Be star
HD169142 probing its protoplanetary disk as close as ~0.1" to the star. Our
images trace the face-on disk out to ~1.7" (~250 AU) and reveal distinct
sub-structures for the first time: 1) the inner disk (<20 AU) appears to be
depleted in scattering dust grains; 2) an unresolved disk rim is imaged at ~25
AU; 3) an annular gap extends from ~40 - 70 AU; 4) local brightness asymmetries
are found on opposite sides of the annular gap. We discuss different
explanations for the observed morphology among which ongoing planet formation
is a tempting - but yet to be proven - one. Outside of ~85 AU the surface
brightness drops off roughly r^{-3.3}, but describing the disk regions between
85-120 AU / 120-250 AU separately with power-laws r^{-2.6} / r^{-3.9} provides
a better fit hinting towards another discontinuity in the disk surface. The
flux ratio between the disk integrated polarized light and the central star is
~4.1 * 10^{-3}. Finally, combining our results with those from the literature,
~40% of the scattered light in the H-band appears to be polarized. Our results
emphasize that HD169142 is an interesting system for future planet formation or
disk evolution studies.


title: Optimal rates of convergence for sparse covariance matrix estimation

abstract:
  This paper considers estimation of sparse covariance matrices and establishes
the optimal rate of convergence under a range of matrix operator norm and
Bregman divergence losses. A major focus is on the derivation of a rate sharp
minimax lower bound. The problem exhibits new features that are significantly
different from those that occur in the conventional nonparametric function
estimation problems. Standard techniques fail to yield good results, and new
tools are thus needed. We first develop a lower bound technique that is
particularly well suited for treating "two-directional" problems such as
estimating sparse covariance matrices. The result can be viewed as a
generalization of Le Cam's method in one direction and Assouad's Lemma in
another. This lower bound technique is of independent interest and can be used
for other matrix estimation problems. We then establish a rate sharp minimax
lower bound for estimating sparse covariance matrices under the spectral norm
by applying the general lower bound technique. A thresholding estimator is
shown to attain the optimal rate of convergence under the spectral norm. The
results are then extended to the general matrix $\ell_w$ operator norms for
$1\le w\le \infty$. In addition, we give a unified result on the minimax rate
of convergence for sparse covariance matrix estimation under a class of Bregman
divergence losses.


title: Attractive Optical Forces from Blackbody Radiation

abstract:
  Blackbody radiation around hot objects induces ac Stark shifts of the energy
levels of nearby atoms and molecules. These shifts are roughly proportional to
the fourth power of the temperature and induce a force decaying with the third
power of the distance from the object. We explicitly calculate the resulting
attractive blackbody optical dipole force for ground state hydrogen atoms.
Surprisingly, this force can surpass the repulsive radiation pressure and
actually pull the atoms against the radiation energy flow towards the surface
with a force stronger than gravity. We exemplify the dominance of the
"blackbody force" over gravity for hydrogen in a cloud of hot dust particles.
This overlooked force appears relevant in various astrophysical scenarios, in
particular, since analogous results hold for a wide class of other broadband
radiation sources.


title: Distributive inverse semigroups and non-commutative Stone dualities

abstract:
  We develop the theory of distributive inverse semigroups as the analogue of
distributive lattices without top element and prove that they are in a duality
with those etale groupoids having a spectral space of identities, where our
spectral spaces are not necessarily compact. We prove that Boolean inverse
semigroups can be characterized as those distributive inverse semigroups in
which every prime filter is an ultrafilter; we also provide a topological
characterization in terms of Hausdorffness. We extend the notion of the patch
topology to distributive inverse semigroups and prove that every distributive
inverse semigroup has a Booleanization. As applications of this result, we give
a new interpretation of Paterson's universal groupoid of an inverse semigroup
and by developing the theory of what we call tight coverages, we also provide a
conceptual foundation for Exel's tight groupoid.


title:
Structural Diversity for Resisting Community Identification in Published
  Social Networks

abstract:
  As an increasing number of social networking data is published and shared for
commercial and research purposes, privacy issues about the individuals in
social networks have become serious concerns. Vertex identification, which
identifies a particular user from a network based on background knowledge such
as vertex degree, is one of the most important problems that has been
addressed. In reality, however, each individual in a social network is inclined
to be associated with not only a vertex identity but also a community identity,
which can represent the personal privacy information sensitive to the public,
such as political party affiliation. This paper first addresses the new privacy
issue, referred to as community identification, by showing that the community
identity of a victim can still be inferred even though the social network is
protected by existing anonymity schemes. For this problem, we then propose the
concept of \textit{structural diversity} to provide the anonymity of the
community identities. The $k$-Structural Diversity Anonymization ($k$-SDA) is
to ensure sufficient vertices with the same vertex degree in at least $k$
communities in a social network. We propose an Integer Programming formulation
to find optimal solutions to $k$-SDA and also devise scalable heuristics to
solve large-scale instances of $k$-SDA from different perspectives. The
performance studies on real data sets from various perspectives demonstrate the
practical utility of the proposed privacy scheme and our anonymization
approaches.


title: Photon gas with hyperbolic dispersion relations

abstract:
  We investigate the density of states for a photon gas confined in a
nonmagnetic metamaterial medium in which some components of the permittivity
tensor are negative. We study the effect of the resulting hyperbolic dispersion
relations on the black body spectral density. We show that for both of the
possible wavevector space topologies, the spectral density vanishes at a
certain frequency. We obtain the partition function and derive some
thermodynamical quantities of the system. To leading order, the results
resemble those of a one- or two-dimensional photon gas with an enhanced density
of states.


title: Yet another approach to the Maximum Flow

abstract:
  I introduce a new approach to the maximum flow problem by a simple algorithm
with a slightly better runtime. This approach is based on sorting arcs insight
of vertices on a residual graph. This new approach leads to an O(mn^0.5) time
bound for a network with n vertices and m arcs.
  Category: Algorithms, Graph Theory and maximum flows


title:
Off-resonant transitions in the collective dynamics of multilevel atomic
  ensembles

abstract:
  We study the contributions of off-resonant transitions to the dynamics of a
system of N multilevel atoms sharing one excitation and interacting with the
quantized vector electromagnetic field. The Rotating Wave Approximation
significantly simplifies the derivation of the equations of motion describing
the collective atomic dynamics, but it leads to an incorrect expression for the
dispersive part of the atom-atom interaction terms. For the case of two-level
atoms and a scalar electromagnetic field, it turns out that the atom-atom
interaction can be recovered correctly if integrals over the photon mode
frequencies are extended to incorporate negative values. We explicitly derive
the atom-atom interaction for multi-level atoms, coupled to the full vector
electromagnetic field, and we recover also in this general case the validity of
the results obtained by the extension to negative frequencies of the formulas
derived with the Rotating Wave Approximation.


title:
Constructive Zermelo-Fraenkel set theory and the limited principle of
  omniscience

abstract:
  In recent years the question of whether adding the limited principle of
omniscience, LPO, to constructive Zermelo-Fraenkel set theory, CZF, increases
its strength has arisen several times. As the addition of excluded middle for
atomic formulae to CZF results in a rather strong theory, i.e. much stronger
than classical Zermelo set theory, it is not obvious that its augmentation by
LPO would be proof-theoretically benign. The purpose of this paper is to show
that CZF +RDC+ LPO has indeed the same strength as CZF, where RDC stands for
relativized dependent choice. In particular, these theories prove the same
Pi-?0-2 theorems of arithmetic.


title: QFT on quantum spacetime: a compatible classical framework

abstract:
  We develop a systematic classical framework to accommodate canonical
quantization of geometric and matter perturbations on a quantum homogeneous
isotropic flat spacetime. The existing approach of standard cosmological
perturbations is indeed proved to be good only up to first order in the
inhomogeneities, and only if the background is treated classically. To
consistently quantize the perturbations \emph{and} the background, a new set of
classical phase space variables is required. We show that, in a natural gauge,
a set of such Dirac observables exists, and their algebra is of the canonical
form. Finally, we compute the physical Hamiltonian that generates the dynamics
of such observables with respect to the homogeneous part of a K-G "clock" field
$T$. The results of this work provide a good starting point to understanding
and calculating effects that quantum cosmological spacetime in the background
has on the quantum perturbations of the metric tensor and of matter fields.


title: A spectral result for Hardy inequalities

abstract:
  Let P be a linear, second order, elliptic operator satisfying a Hardy
inequality with potential W (i.e. $P-W\geq0$) and best constant $\alpha$. We
give conditions so that the spectrum of $W^{-1}P$ is $[\alpha,\infty)$. We
apply this to several well-known Hardy inequalities: (improved) Hardy
inequalities on a bounded convex domain with potential involving the distance
to the boundary, and Hardy inequalities for minimal submanifolds of the
Euclidean space.


title:
Measuring and engineering entropy and spin squeezing in weakly linked
  Bose-Einstein condensates

abstract:
  We propose a method to infer the single-particle entropy of bosonic atoms in
an optical lattice and to study the local evolution of entropy, spin squeezing,
and entropic inequalities for entanglement detection in such systems. This
method is based on experimentally feasible measurements of
non-nearest-neighbour coherences. We study a specific example of dynamically
controlling atom tunneling between selected sites and show that this could
potentially also improve the metrologically relevant spin squeezing.


title: Stationary max-stable processes with the Markov property

abstract:
  We prove that the class of discrete time stationary max-stable process
satisfying the Markov property is equal, up to time reversal, to the class of
stationary max-autoregressive processes of order $1$. A similar statement is
also proved for continuous time processes.


title: Ideal strength of random alloys from first-principles theory

abstract:
  The all-electron exact muffin-tin orbitals method in combination with the
coherent-potential appproximation has been employed to investigate the ideal
tensile strengths of elemental V, Mo solids and V- and Mo-based random solid
solutions. The present ideal tensile strengths, calculated assuming isotropic
Poisson contraction, are 16.1, 26.7 and 37.6 GPa for bcc V in the [001], [111]
and [110] directions, respectively, and 26.7 GPa for bcc Mo in the [001]
direction, which are all in good agreement with the available theoretical data.
When a few percent Tc is introduced in Mo, it is found that the ideal strength
decreases in the [001] direction. For the V-based alloys, Cr increases and Ti
decreases the ideal tensile strength in all principal directions. Adding the
same concentration of Cr and Ti to V leads to ternary alloys with similar ideal
strength values as that of pure V. The alloying effects on the ideal strength
is explained using the electronic band structure.


title: On the multi dimensional modal logic of substitutions

abstract:
  We prove completeness, interpolation, decidability and an omitting types
theorem for certain multi dimensional modal logics where the states are not
abstract entities but have an inner structure. The states will be sequences.
Our approach is algebraic addressing (varieties generated by) complex algebras
of Kripke semantics for such logic. Those algebras, whose elements are sets of
states are common reducts of cylindric and polyadic algebras


title: Decomposition of groups and Top couples

abstract:
  Recently, we have endowed various categories of groups with topologies. The
purpose of this paper is to introduce on these categories others topologies
which are statistically more suitable to study well-known problems in groups
theory. We use this framework to define a notion of prime ideal and to provide
a decomposition of a large class of groups into a product of prime Remark that
a similar question has been studied in [5] by Kurata with innocent methods. We
remark that these topologies can be extended to other categories like the
categories of commutative algebras, associative algebras and left symmetric
algebras.


title:
Game Theoretic Analysis of Production-Management Effort Distribution in
  Organizational Networks

abstract:
  Organizations consist of individuals connected by their responsibilities,
incentives, and reporting structure. These connections are aptly represented by
a network, hierarchical or other, which is often used to divide tasks. A
primary goal of the organization as a whole is to maximize the net productive
output. Individuals in these networks trade off between their productive and
managing efforts to perform these tasks and the trade-off is influenced by
their positions and share of rewards in the network. Efforts of the agents here
are substitutable, e.g., the increase in the productive effort by an individual
in effect reduces the same of some other individual in the network, who now
puts their efforts into management. The management effort of an agent improves
the productivity of certain other agents in the network.
  In this paper, we carry out a detailed game-theoretic analysis of
individual's equilibrium split of efforts into multiple components when
connected over a network. We provide a design recipe of the reward sharing
scheme that maximizes the net productive output. Our results show that under
the strategic behavior of the agents, it may not always be possible to achieve
the optimal output using an idea from game theory called the price of anarchy.


title:
Ferromagnetism and the formation of interlayer As2-dimers in
  Ca(Fe1-xNix)2As2

abstract:
  The compounds Ca(Fe1-xNix)2As2 with the tetragonal ThCr2Si2-type structure
(space group I4/mmm) show a continuous transition of the interlayer As-As
distances from a non-bonding state in CaFe2As2 (dAs-As = 313 pm) to
single-bonded As2-dimers in CaNi2As2 (dAs-As = 260 pm). Magnetic measurements
reveal weak ferromagnetism which develops near the composition
Ca(Fe0.5Ni0.5)2As2, while the compounds with lower and higher nickel
concentrations both are Pauli-paramagnetic. DFT band structure calculations
reveal that the As2-dimer formation is a consequence of weaker metal-metal in
MAs4-layers (M = Fe1-xNix) of Ni-richer compounds, and depends not on
depopulation or shift of As-As antibonding states as suggested earlier. Our
results also indicate that the ferromagnetism of Ca(Fe0.5Ni0.5)2As2 and related
compounds like SrCo2(Ge0.5P0.5)2 is probably not induced by dimer breaking as
recently suggested, but arises from the high density of states generated by the
transition metal 3d bands near the Fermi level without contribution of the
dimers.


title: Hodge numbers for the cohomology of Calabi-Yau type local systems

abstract:
  We use Higgs cohomology to determine the Hodge numbers of the first
intersection cohomology group of a local system V arising from the third direct
image of a family of Calabi-Yau 3-folds over a smooth, quasi-projective curve.
We give applications to Rhode's families of Calabi-Yau 3-folds without MUM.


title: Matter and Ricci collineations

abstract:
  The infinitesimal transformations that leave invariant a two-covariant
symmetric tensor are studied. The interest of these symmetry transformations
lays in the fact that this class of tensors includes the energy-momentum and
Ricci tensors. We find that in most cases the class of infinitesimal generators
of these transformations is a finite dimensional Lie algebra but also, in some
cases exhibiting a higher degree of degeneracy, this class is infinite
dimensional and may fail to be a Lie algebra.


title:
Local mechanical response in semiflexible polymer networks subjected to
  an axisymmetric prestress

abstract:
  Analytical and numerical calculations are presented for the mechanical
response of fiber networks in a state of axisymmetric prestress, in the limit
where geometric non-linearities such as fiber rotation are negligible. This
allows us to focus on the anisotropy deriving purely from the non-linear
force-extension curves of individual fibers. The number of independent elastic
coefficients for isotropic, axisymmetric and fully anisotropic networks are
enumerated, before deriving expressions for the response to a locally applied
force that can be tested against e.g. microrheology experiments. Localised
forces can generate anisotropy away from the point of application, so numerical
integration of non-linear continuum equations is employed to determine the
stress field, and induced mechanical anisotropy, at points located directly
behind and in front of a force monopole. Results are presented for the wormlike
chain model in normalised forms, allowing them to be easily mapped to a range
of systems. Finally, the relevance of these findings to naturally occurring
systems and directions for future investigation are discussed.


title:
The high-pressure superconductivity in SiH4: the strong-coupling
  approach

abstract:
  In the paper, the thermodynamic parameters of the high-pressure
superconducting state in the SiH$_4$ compound have been determined ($p=250$
GPa). By using the Eliashberg equations in the mixed representation, the
critical temperature, the energy gap, and the electron effective mass have been
calculated. It has been stated that the critical temperature ($T_{C}$)
decreases from 51.65 K to 20.62 K, if the Coulomb pseudopotential increases
($\mu^{\star}\in 0.1,0.3$). The dimensionless ratio $2\Delta\(0\)/k_{B}T_{C}$
decreases from 4.10 to 3.84, where the symbol $\Delta\(0\)$ denotes the value
of the order parameter close to the zero temperature. The ratio of the electron
effective mass to the band electron mass is high, and it reaches maximum equal
to 1.95 for the critical temperature.


title:
Some Properties of Generalized Self-reciprocal Polynomials over Finite
  Fields

abstract:
  Numerous results on self-reciprocal polynomials over finite fields have been
studied. In this paper we generalize some of these to a-self reciprocal
polynomials defined in [4]. We consider some properties of the divisibility of
a-reciprocal polynomials and characterize the parity of the number of
irreducible factors for a-self reciprocal polynomials over finite fields of odd
characteristic.


title: Marginally outer trapped surfaces in higher dimensions

abstract:
  We review the basic setup of Kaluza-Klein theory, namely a 5-dimensional
vacuum with a cyclic isometry, which corresponds to Einstein-Maxwell-dilaton
theory in 4-dimensional spacetime. We first recall the behaviour of Killing
horizons and its generators under bundle lift and projection. We then show that
the property of compact surfaces of being (stably) marginally trapped is
preserved under lift and projection provided the appropriate ("Pauli-")
conformal scaling is used for the spacetime metric. We also discuss and compare
recently proven area inequalities for stable axially symmetric 2-dimensional
and 3-dimensional marginally outer trapped surfaces.


title:
Reliability estimators for the components of series and parallel
  systems: The Weibull model

abstract:
  This paper presents a hierarchical Bayesian approach to the estimation of
components' reliability (survival) using a Weibull model for each of them. The
proposed method can be used to estimation with general survival censored data,
because the estimation of a component's reliability in a series (parallel)
system is equivalent to the estimation of its survival function with right-
(left-) censored data. Besides the Weibull parametric model for reliability
data, independent gamma distributions are considered at the first hierarchical
level for the Weibull parameters and independent uniform distributions over the
real line as priors for the parameters of the gammas. In order to evaluate the
model, an example and a simulation study are discussed.


title:
Performances of a GEM-based Time Projection Chamber prototype for the
  AMADEUS experiment

abstract:
  A large number of high-energy and heavy-ion experiments successfully used
Time Projection Chamber (TPC) as central tracker and particle identification
detector. However, the performance requirements on TPC for new high-rate
particle experiments greatly exceed the abilities of traditional TPC read out
by multi-wire proportional chamber (MWPC). Gas Electron Multiplier (GEM)
detector has great potential to improve TPC performances when used as
amplification device. In this paper we present the R&D activity on a new
GEM-based TPC detector built as a prototype for the inner part for AMADEUS, a
new experimental proposal at the DAFNE collider at Laboratori Nazionali di
Frascati (INFN), aiming to perform measurements of the low-energy negative
kaons interactions in nuclei. In order to evaluate the GEM-TPC performances, a
10x10 cm2 prototype with a drift gap up to 15 cm has been realized. The
detector was tested at the pM1 beam facility of the Paul Scherrer Institut
(PSI) with low momentum pions and protons, without magnetic field. Drift
properties of argonisobutane gas mixtures are measured and compared
withMagboltz prediction. Detection efficiency and spatial resolution as a
function of a large number of parameters, such as the gas gain, the drift
field, the front-end electronic threshold and particle momentum, are
illustrated and discussed. Particle identification capability and the
measurement of the energy resolution in isobutane-based gas mixture are also
reported.


title: Cosmological dynamics of a hybrid chameleon scenario

abstract:
  We consider a hybrid scalar field which is non-minimally coupled to the
matter and models a chameleon cosmology. By introducing an effective potential,
we study the dependence of the effective potential's minimum and hybrid
chameleon field's masses to the local matter density. In a dynamical system
technique, we analyze the phase space of this two-field chameleon model, find
its fixed points and study their stability. We show that the hybrid chameleon
domination solution is a stable attractor and the universe in this setup
experiences a phantom divide crossing.


title:
Signatures of anisotropic sources in the squeezed-limit bispectrum of
  the cosmic microwave background

abstract:
  The bispectrum of primordial curvature perturbations in the squeezed
configuration, in which one wavenumber, $k_3$, is much smaller than the other
two, $k_3\ll k_1\approx k_2$, plays a special role in constraining the physics
of inflation. In this paper we study a new phenomenological signature in the
squeezed-limit bispectrum: namely, the amplitude of the squeezed-limit
bispectrum depends on an angle between ${\bf k}_1$ and ${\bf k}_3$ such that
$B_\zeta(k_1, k_2, k_3) \to 2 \sum_L c_L P_L(\hat{\bf k}_1 \cdot \hat{\bf k}_3)
P_\zeta(k_1)P_\zeta(k_3)$, where $P_L$ are the Legendre polynomials. While
$c_0$ is related to the usual local-form $f_{\rm NL}$ parameter as $c_0=6f_{\rm
NL}/5$, the higher-multipole coefficients, $c_1$, $c_2$, etc., have not been
constrained by the data. Primordial curvature perturbations sourced by
large-scale magnetic fields generate non-vanishing $c_0$, $c_1$, and $c_2$.
Inflation models whose action contains a term like $I(\phi)^2 F^2$ generate
$c_2=c_0/2$. A recently proposed "solid inflation" model generates $c_2\gg
c_0$. A cosmic-variance-limited experiment measuring temperature anisotropy of
the cosmic microwave background up to $\ell_{\rm max}=2000$ is able to measure
these coefficients down to $\delta c_0=4.4$, $\delta c_1=61$, and $\delta
c_2=13$ (68% CL). We also find that $c_0$ and $c_1$, and $c_0$ and $c_2$, are
nearly uncorrelated. Measurements of these coefficients will open up a new
window into the physics of inflation such as the existence of vector fields
during inflation or non-trivial symmetry structure of inflaton fields. Finally,
we show that the original form of the Suyama-Yamaguchi inequality does not
apply to the case involving higher-spin fields, but a generalized form does.


title: Building a reordering system using tree-to-string hierarchical model

abstract:
  This paper describes our submission to the First Workshop on Reordering for
Statistical Machine Translation. We have decided to build a reordering system
based on tree-to-string model, using only publicly available tools to
accomplish this task. With the provided training data we have built a
translation model using Moses toolkit, and then we applied a chart decoder,
implemented in Moses, to reorder the sentences. Even though our submission only
covered English-Farsi language pair, we believe that the approach itself should
work regardless of the choice of the languages, so we have also carried out the
experiments for English-Italian and English-Urdu. For these language pairs we
have noticed a significant improvement over the baseline in BLEU, Kendall-Tau
and Hamming metrics. A detailed description is given, so that everyone can
reproduce our results. Also, some possible directions for further improvements
are discussed.


title:
The stability problem and special solutions for the 5-components
  Maxwell-Bloch equations

abstract:
  For the 5-components Maxwell-Bloch system the stability problem for the
isolated equilibria is completely solved. Using the geometry of the symplectic
leaves, a detailed construction of the homoclinic orbits is given. Studying the
problem of invariant sets for the system we discover a rich family of periodic
solutions in explicit form.


title:
Steinberg presentations of black box classical groups in small
  characteristics

abstract:
  The main component of (constructive) recognition algorithms for black box
groups of Lie type in computational group theory is the construction of
unipotent elements. In the existing algorithms unipotent elements are found by
random search and therefore the running time of these algorithms is polynomial
in the underlying field size $q$ which makes them unfeasible for most practical
applications \cite{guralnick01.169}. Meanwhile, the input size of recognition
algorithms involves only $\log q$. The present paper introduces a new approach
to construction of unipotent elements in which the running time of the
algorithm is quadratic in characteristic $p$ of the underlying field and is
polynomial in $\log q$; for small values of $p$ (which make a vast and
practically important class of problems), the complexity of these algorithms is
polynomial in the input size.
  For $\psl_2(q)$, $\qpone$, we present a Monte-Carlo algorithm which
constructs a root subgroup $U$, the maximal torus $T$ normalizing $U$ and a
Weyl group element $w$ which conjugates $U$ to its opposite. Moreover, we
extend this result and construct Steinberg generators for the black box
untwisted classical groups defined over a field of odd size $q=p^k$ where
$\qpone$. Our algorithms run in time quadratic in characteristic $p$ of the
underlying field and polynomial in $\log q$ and the Lie rank $n$ of the group.
  The case $\qmone$ requires the use of additional tools and is treated
separately in our next paper \cite{suko12B}. Further, and much stronger results
can be found in \cite{suko12E,suko12F}.


title: Kirillov models and the Breuil-Schneider conjecture for GL_2(F)

abstract:
  Let F be a local field of characteristic 0. The Breuil-Schneider conjecture
for GL_2(F) predicts which locally algebraic representations of this group
admit an integral structure. We extend the methods of [K-dS12], which treated
smooth representations only, to prove the conjecture for some locally algebraic
representations as well.


title: Modified Brans-Dicke theory with space-time anisotropic parameters

abstract:
  We consider the ADM formalism of the Brans-Dicke theory and propose an
anisotropic extension of the theory by introducing five free parameters. We
find that the resulting theory reveals many interesting aspects which are not
present in the original BD theory. We first discuss the ghost instability and
strong coupling problems which are present in the gravity theory without the
full diffeomorphism symmetry and show that they can be avoided in a region of
the parameter space. We also perform the post-Newtonian approximation and show
that the constraint of the Brans-Dicke parameter $\omega_{{\rm BD}}$ being
large to be consistent with the solar system observations could be evaded in
the extended theory. We also discuss that accelerating Universe can be achieved
without the need of the potential for the Brans-Dicke scalar.


title: Theory of ferromagnetism in vanadium-oxide based perovskites

abstract:
  The conditions under which ferromagnetism may occur in transition metal
oxides with partially filled $t_{2g}$ shells such as vanadium-based perovskites
are studied using a combination of density functional and single-site dynamical
mean field methods. For reasonable values of the correlation strength,
rotations of the VO$_6$ octahedra play an important role in enabling
ferromagnetism, with ferromagnetism typically occurring for rotations larger
than a nonzero critical value. Ferromagnetism is suppressed near the Mott
insulating phase but the phase boundary is otherwise only weakly dependent on
carrier concentration. Design rules are suggested for new oxide systems
exhibiting ferromagnetism.


title: A three-beam setup for coherently controlling nuclear state population

abstract:
  The controlled transfer of nuclear state population using two x-ray laser
pulses is investigated theoretically. The laser pulses drive two nuclear
transitions in a nuclear three-level system facilitating coherent population
transfer via the quantum optics technique of stimulated Raman adiabatic
passage. To overcome present limitations of the x-ray laser frequency, we
envisage accelerated nuclei interacting with two copropagating or crossed x-ray
laser pulses in a three-beam setup. We present a systematic study of this setup
providing both pulse temporal sequence and laser pulse intensity for optimized
control of the nuclear state population. The tolerance for geometrical
parameters such as laser beam divergence of the three-beam setup as well as for
the velocity spread of the nuclear beam are studied and a two-photon resonance
condition to account for experimental uncertainties is deduced. This additional
condition gives a less strict requirement for the experimental implementation
of the three-beam setup. Present experimental state of the art and future
prospects are discussed.


title:
Bounding Castelnuovo-Mumford regularity of graphs via Lozin's
  transformation

abstract:
  We prove that when a Lozin's transformation is applied to a graph, the
(Castelnuovo-Mumford) regularity of the graph increases exactly by one, as it
happens to its induced matching number. As a consequence, we show that the
regularity of a graph can be bounded from above by a function of its induced
matching number. We also prove that the regularity of a graph is always less
than or equal to the sum of its induced matching and decycling numbers.


title: Bayesian analysis of measurement error models using INLA

abstract:
  To account for measurement error (ME) in explanatory variables, Bayesian
approaches provide a flexible framework, as expert knowledge about unobserved
covariates can be incorporated in the prior distributions. However, given the
analytic intractability of the posterior distribution, model inference so far
has to be performed via time-consuming and complex Markov chain Monte Carlo
implementations. In this paper we extend the Integrated nested Laplace
approximations (INLA) approach to formulate Gaussian ME models in generalized
linear mixed models. We present three applications, and show how parameter
estimates are obtained for common ME models, such as the classical and Berkson
error model including heteroscedastic variances. To illustrate the practical
feasibility, R-code is provided.


title:
Strictly static spacetimes and positive mass in the
  Einstein-Gauss-Bonnet theory

abstract:
  In the Einstein gravity, it is well-known that strictly stationary and vacuum
regular spacetime should be the Minkowski spacetime. In the
Einstein-Gauss-Bonnet theory, we shall show the similar statement, that is,
strictly static(no event horizon), vacuum and asymptotically flat spacetimes
with conformally static slices are the Minkowski spacetime when the curvature
corrections are small.


title:
Nucleosynthesis in the gamma-ray burst accretion disks and associated
  outflows

abstract:
  We investigate nucleosynthesis inside the gamma-ray burst (GRB) accretion
disks formed by the Type II collapsars and outflows launched from these disks.
We deal with accretion disks having relatively low accretion rates: 0.001 M_sun
s^{-1} <~ Mdot <~ 0.01 M_sun s^{-1} and hence they are predominantly advection
dominated. We report the synthesis of several unusual nuclei like 31P, 39K,
43Sc, 35Cl and various isotopes of titanium, vanadium, chromium, manganese and
copper in the disk. We also confirm that isotopes of iron, cobalt, nickel,
argon, calcium, sulphur and silicon get synthesized in the disk, as shown by
previous authors. Much of these heavy elements thus synthesized are ejected
from the disk and survive in the outflows. Indeed, emission lines of many of
these heavy elements have been observed in the X-ray afterglows of several
GRBs.


title: The Ljapunov-Schmidt reduction for some critical problems

abstract:
  This is a survey about the application of the Ljapunov-Schmidt reduction for
some critical problems.


title:
Tail asymptotic of the stationary distribution for the state dependent
  (1,R)-reflecting random walk: near critical

abstract:
  In this paper, we consider the $(1,R)$ state-dependent reflecting random walk
(RW) on the half line, allowing the size of jumps to the right at maximal $R$
and to the left only 1. We provide an explicit criterion for positive
recurrence and the explicit expression of the stationary distribution based on
the intrinsic branching structure within the walk. As an application, we obtain
the tail asymptotic of the stationary distribution in the "near critical"
situation.


title: Squared Eigenfunction Symmetries for the BTL and CTL Hierarchies

abstract:
  In this paper, the squared eigenfunction symmetries for the BTL and CTL
hierarchies are explicitly constructed with the suitable modification of the
ones for the TL hierarchy, by considering the BTL and CTL constraints. Also the
connections with the corresponding additional symmetries are investigated: the
squared eigenfunction symmetry generated by the wave function can be viewed as
the generating function for the additional symmetries.


title: A penalized empirical likelihood method in high dimensions

abstract:
  This paper formulates a penalized empirical likelihood (PEL) method for
inference on the population mean when the dimension of the observations may
grow faster than the sample size. Asymptotic distributions of the PEL ratio
statistic is derived under different component-wise dependence structures of
the observations, namely, (i) non-Ergodic, (ii) long-range dependence and (iii)
short-range dependence. It follows that the limit distribution of the proposed
PEL ratio statistic can vary widely depending on the correlation structure, and
it is typically different from the usual chi-squared limit of the empirical
likelihood ratio statistic in the fixed and finite dimensional case. A unified
subsampling based calibration is proposed, and its validity is established in
all three cases, (i)-(iii). Finite sample properties of the method are
investigated through a simulation study.


title:
Constraining the initial conditions of globular clusters using their
  radius distribution

abstract:
  Studies of extra-galactic globular clusters have shown that the peak size of
the globular cluster (GC) radius distribution (RD) depends only weakly on
galactic environment, and can be used as a standard ruler. We model RDs of GC
populations using a simple prescription for a Hubble time of relaxation driven
evolution of cluster mass and radius, and explore the conditions under which
the RD can be used as a standard ruler. We consider a power-law cluster initial
mass function (CIMF) with and without an exponential truncation, and focus in
particular on a flat and a steep CIMF (power-law indices of 0 and -2,
respectively). For the initial half-mass radii at birth we adopt either
Roche-lobe filling conditions ('filling',meaning that the ratio of half-mass to
Jacobi radius is approximately rh/rJ ~ 0.15) or strongly Roche-lobe
under-filling conditions ('under-filling', implying that initially rh/rJ <<
0.15). Assuming a constant orbital velocity about the galaxy centre we find for
a steep CIMF that the typical half-light radius scales with galactocentric
radius RG as RG^1/3. This weak scaling is consistent with observations, but
this scenario has the (well known) problem that too many low-mass clusters
survive. A flat CIMF with 'filling' initial conditions results in the correct
mass function at old ages, but with too many large (massive) clusters at large
RG. An 'underfilling' GC population with a flat CIMF also results in the
correct mass function, and can also successfully reproduce the shape of the RD,
with a peak size that is (almost) independent of RG. In this case, the peak
size depends (almost) only on the peak mass of the GC mass function. The (near)
universality of the GC RD is therefore because of the (near) universality of
the CIMF. There are some extended GCs in the outer halo of the Milky Way that
cannot be explained by this model.


title:
On the validity of the paraxial approximation for electron acceleration
  with radially polarized laser beams

abstract:
  In the study of laser-driven electron acceleration, it has become customary
to work within the framework of paraxial wave optics. Using an exact solution
to the Helmholtz equation as well as its paraxial counterpart, we perform
numerical simulations of electron acceleration with a high-power TM01 beam. For
beam waist sizes at which the paraxial approximation was previously recognized
valid, we highlight significant differences in the angular divergence and
energy distribution of the electron bunches produced by the exact and the
paraxial solutions. Our results demonstrate that extra care has to be taken
when working under the paraxial approximation in the context of electron
acceleration with radially polarized laser beams.


title:
A random coordinate descent algorithm for optimization problems with
  composite objective function and linear coupled constraints

abstract:
  In this paper we propose a variant of the random coordinate descent method
for solving linearly constrained convex optimization problems with composite
objective functions. If the smooth part of the objective function has Lipschitz
continuous gradient, then we prove that our method obtains an
$\epsilon$-optimal solution in ${\cal O}(N^2/\epsilon)$ iterations, where $N$
is the number of blocks. For the class of problems with cheap coordinate
derivatives we show that the new method is faster than methods based on
full-gradient information. Analysis for the rate of convergence in probability
is also provided. For strongly convex functions our method converges linearly.
Extensive numerical tests confirm that on very large problems, our method is
much more numerically efficient than methods based on full gradient
information.


title: Remarks on step cocycles over rotations, centralizers and coboundaries

abstract:
  By using a cocycle generated by the step function $\varphi_{\beta, \gamma} =
1_{[0, \beta]} - 1_{[0, \beta]} (. + \gamma)$ over an irrational rotation $x
\to x + \alpha \mod 1$, we present examples which illustrate different aspects
of the general theory of cylinder maps. In particular, we construct non ergodic
cocycles with ergodic compact quotients, cocycles generating an extension
$T_{\alpha, \varphi}$ with a small centralizer. The constructions are related
to diophantine properties of $\alpha, \beta, \gamma$.


title:
Arbitrary-Lagrangian-Eulerian One-Step WENO Finite Volume Schemes on
  Unstructured Triangular Meshes

abstract:
  In this article we present a new class of high order accurate
Arbitrary-Eulerian-Lagrangian (ALE) one-step WENO finite volume schemes for
solving nonlinear hyperbolic systems of conservation laws on moving two
dimensional unstructured triangular meshes. A WENO reconstruction algorithm is
used to achieve high order accuracy in space and a high order one-step time
discretization is achieved by using the local space-time Galerkin predictor.
For that purpose, a new element--local weak formulation of the governing PDE is
adopted on moving space--time elements. The space-time basis and test functions
are obtained considering Lagrange interpolation polynomials passing through a
predefined set of nodes. Moreover, a polynomial mapping defined by the same
local space-time basis functions as the weak solution of the PDE is used to map
the moving physical space-time element onto a space-time reference element. To
maintain algorithmic simplicity, the final ALE one-step finite volume scheme
uses moving triangular meshes with straight edges. This is possible in the ALE
framework, which allows a local mesh velocity that is different from the local
fluid velocity. We present numerical convergence rates for the schemes
presented in this paper up to sixth order of accuracy in space and time and
show some classical numerical test problems for the two-dimensional Euler
equations of compressible gas dynamics.


title:
Extremum seeking via continuation techniques for optimizing biogas
  production in the chemostat

abstract:
  We consider the chemostat model with the substrate concentration as the
single measurement. We propose a control strategy that drives the system at a
steady state maximizing the gas production without the knowledge of the
specific growth rate. Our approach separates the extremum seeking problem from
the feedback control problem such that each of the two subproblems can be
solved with relatively simple algorithms. We are then free to choose any
numerical optimization algorithm. We give a demonstration for two choices: one
is based on slow-fast dynamics and numerical continuation, the other is a
combination of golden-section and Newton iteration. The method copes with
non-monotonic growth functions.


title: Local and global tameness in Krull monoids

abstract:
  Let H be a Krull monoid with finite class group G such that every class
contains a prime divisor. Then the global tame degree t (H) equals zero if and
only if H is factorial (equivalently, |G|=1). If |G| > 1, then D (G) <= t (H)
<= 1 + D (G) (D (G) -1) / 2, where D (G) is the Davenport constant of G. We
analyze the case when t (H) equals the lower bound, and we show that t (H)
grows asymptotically as the upper bound, when both terms are considered as
functions of the rank of G. We provide more precise results if G is either
cyclic or an elementary 2-group.


title:
Exponential growth of homological torsion for towers of congruence
  subgroups of Bianchi groups

abstract:
  In this paper we prove that for suitable sequences of congruence subgroups of
Bianchi groups, including the standard exhaustive sequences of a congruence
subgroup, and even symmetric powers of the standard representation of Sl_2(C)
the size of the torsion part in the first homology grows exponentially. This
extends results of Bergeron and Venkatesh to a case of non-uniform lattices.


title: Dynamics of Supersymmetric Chameleons

abstract:
  We investigate the cosmological dynamics of a class of supersymmetric
chameleon models coupled to cold dark matter fermions. Supergravity corrections
ensure that these models are efficiently screened in all astrophysical objects
of interest, however this does not preclude the enhancement of gravity on
linear cosmological scales. We analyse the background cosmology and solve the
modified equations for the growth of cold dark matter density perturbations in
closed form. Using this, we go on to derive the modified linear power spectrum
which is characterised by two scales, the horizon size at matter-radiation
equality and at the redshift when the chameleon reaches the minimum of its
effective potential. The model includes a cosmological constant in the form of
a Fayet-Illiopolous term, which emerges at late times due to the coupling of
the chameleon to two charged scalars. We examine the conditions under which
this leads to viable background cosmology and go on to analyse the deviations
from the LCDM predictions in the linear regime. We find that for reasonable
values in the model's parameter space there is generically a region where the
model's cosmology is viable and current measurements can be reproduced. A small
discrepancy of the matter power spectrum from its LCDM counterpart can be
obtained in a smaller subset of the parameter space.


title: Distinct distances on two lines

abstract:
  Let P_1 and P_2 be two sets of points in the plane, so that P_1 is contained
in a line L_1, P_2 is contained in a line L_2, and L_1 and L_2 are neither
parallel nor orthogonal. Then the number of distinct distances determined by
the pairs of P_1xP_2 is \Omega(\min{|P_1|^{2/3}|P_2|^{2/3},|P_1|^2, |P_2|^2}).
  In particular, if |P_1|=|P_2|=m, then the number of these distinct distances
is \Omega(m^{4/3}), improving upon the previous bound \Omega(m^{5/4}) of
Elekes.