title:
On the Properties of Inner Cool Disks in the Hard State of Black Hole
  X-Ray Transient Systems

abstract:
  The formation of a cool disk in the innermost regions of black hole X-ray
transient systems in the low hard state is investigated. Taking into account
the combined cooling associated with the Compton and conductive energy
transport processes in a corona, the radial structure of a disk is described
for a range of mass accretion rates. The mass flow in an optically thick inner
region can be maintained by the condensation of matter from a corona with the
disk temperature and luminosity varying continuously as a function of the
accretion rate. Although such a disk component can be present, the contribution
of the optically thick disk component to the total luminosity can be small
since the mass flow due to condensation in the optically thick disk underlying
the corona can be significantly less than the mass flow rate in the corona. The
model is applied to the observations of the low quiescent state of the black
hole source GX 339-4 at luminosities of around $0.01 L_{Edd}$ and is able to
explain the temperature of the thermal component at the observed luminosities.
Since conductive cooling dominates Compton cooling at low mass accretion rates,
the luminosity corresponding to the critical mass accretion rate above which a
weak thermal disk component can be present in the low hard state is estimated
to be as low as $0.001 L_{Edd}$.


title: System overview of the VLTI Spectro-Imager

abstract:
  The VLTI Spectro Imager project aims to perform imaging with a temporal
resolution of 1 night and with a maximum angular resolution of 1
milliarcsecond, making best use of the Very Large Telescope Interferometer
capabilities. To fulfill the scientific goals (see Garcia et. al.), the system
requirements are: a) combining 4 to 6 beams; b) working in spectral bands J, H
and K; c) spectral resolution from R= 100 to 12000; and d) internal fringe
tracking on-axis, or off-axis when associated to the PRIMA dual-beam facility.
The concept of VSI consists on 6 sub-systems: a common path distributing the
light between the fringe tracker and the scientific instrument, the fringe
tracker ensuring the co-phasing of the array, the scientific instrument
delivering the interferometric observables and a calibration tool providing
sources for internal alignment and interferometric calibrations. The two
remaining sub-systems are the control system and the observation support
software dedicated to the reduction of the interferometric data. This paper
presents the global concept of VSI science path including the common path, the
scientific instrument and the calibration tool. The scientific combination
using a set of integrated optics multi-way beam combiners to provide
high-stability visibility and closure phase measurements are also described.
Finally we will address the performance budget of the global VSI instrument.
The fringe tracker and scientific spectrograph will be shortly described.


title: Monodromy and isotopy of monotone Lagrangian tori

abstract:
  We define new Hamiltonian isotopy invariants for a monotone Lagrangian torus
embedded in a symplectic 4-manifold. We show that, in the standard symplectic
4-space, these invariants distinguish a monotone Clifford torus from a Chekanov
torus.


title:
Geometric Phase for Non-Hermitian Hamiltonians and Its Holonomy
  Interpretation

abstract:
  For an arbitrary possibly non-Hermitian matrix Hamiltonian H, that might
involve exceptional points, we construct an appropriate parameter space M and
the lines bundle L^n over M such that the adiabatic geometric phases associated
with the eigenstates of the initial Hamiltonian coincide with the holonomies of
L^n. We examine the case of 2 x 2 matrix Hamiltonians in detail and show that,
contrary to claims made in some recent publications, geometric phases arising
from encircling exceptional points are generally geometrical and not
topological in nature.


title: A generalization of Cobham's Theorem

abstract:
  If a non-periodic sequence $X$ is the image by a morphism of a fixed point of
both a primitive substitution $\sigma$ and a primitive substitution $\tau$,
then the dominant eigenvalues of the matrices of $\sigma$ and of $\tau$ are
multiplicatively dependent. This is the way we propose to generalize Cobham's
Theorem.


title: Proton channels

abstract:
  The structure of Nafion, the polymer electrolyte membrane used in some fuel
cells, has been extensively debated over recent decades. Now, a newly proposed
model reveals the nanoscale arrangement that could explain the excellent
transport properties of the material.


title:
Doppler-free spectroscopy of the 1S0-3P0 optical clock transition in
  laser-cooled fermionic isotopes of neutral mercury

abstract:
  We have performed for the first time direct laser spectroscopy of the 1S0-3P0
optical clock transition at 265.6 nm in fermionic isotopes of neutral mercury
laser-cooled in a magneto-optical trap. Spectroscopy is performed by measuring
the depletion of the magneto-optical trap induced by the excitation of the
long-lived 3P0 state by a probe at 265.6 nm. Measurements resolve the
Doppler-free recoil doublet allowing for a determination of the transition
frequency to an uncer- tainty well below the Doppler-broadened linewidth. We
have performed absolute measurement of the frequency with respect to an
ultra-stable reference monitored by LNE-SYRTE fountain pri- mary frequency
standards using a femtosecond laser frequency comb. The measured frequency is
1128575290808 +/- 5.6 kHz in 199Hg and 1128569561140 +/- 5.3 kHz in 201Hg, more
than 4 orders of magnitude better than previous indirect determinations. Owing
to a low sensitivity to blackbody radiation, mercury is a promising candidate
for reaching the ultimate performance of optical lattice clocks.


title: Instantons and Wormholes for the Universal Hypermultiplet

abstract:
  In this paper we present supersymmetric instanton and non-supersymmetric
wormhole solutions for the universal hypermultiplet sector of $d=4$ N=2
supergravity theories. Instantons and wormholes are constructed as saddle
points dominating transition amplitudes between states of definite axionic
shift charge, using an approach due to Coleman and Lee. Our solutions are
constructed in terms of the conserved Noether charges associated with the
global SU(2,1) symmetry of the universal hypermultiplet action. The conditions
imposed by regularity on the charges are discussed.


title: Building Hyper Dirichlet Processes for Graphical Models

abstract:
  Graphical models are used to describe the conditional independence relations
in multivariate data. They have been used for a variety of problems, including
log-linear models (Liu and Massam, 2006), network analysis (Holland and
Leinhardt, 1981; Strauss and Ikeda, 1990; Wasserman and Pattison, 1996;
Pattison and Wasserman, 1999; Robins et al., 1999);, graphical Gaussian models
(Roverato and Whittaker, 1998; Giudici and Green, 1999; Marrelec and Benali,
2006), and genetics (Dobra et al., 2004). A distribution that satisfies the
conditional independence structure of a graph is Markov. A graphical model is a
family of distributions that is restricted to be Markov with respect to a
certain graph. In a Bayesian problem, one may specify a prior over the
graphical model. Such a prior is called a hyper Markov law if the random
marginals also satisfy the independence constraints. Previous work in this area
includes (Dempster, 1972; Dawid and Lauritzen, 1993; Giudici and Green, 1999;
Letac and Massam, 2007). We explore graphical models based on a non-parametric
family of distributions, developed from Dirichlet processes.


title:
Waiting time distributions of electron transfers through quantum dot
  Aharonov-Bohm interferometers

abstract:
  We present a statistical readout method for quantum interferences based on
time series analysis of consecutive single electron transfers through a double
quantum dot Aharonov-Bohm interferometer. Waiting time distributions
qualitatively indicate the presence of interferences and provide information on
orbital-detuning and coherent interdot-electron transfer. Interdot transfer
induced oscillations are Aharonov-Bohm phase sensitive, while those due to
level detuning are phase-independent. The signature of the quantum interference
in the waiting time distribution is more apparent for weakly coupled electron
transfer detectors.


title: Almost Vanishing Polynomials for Sets of Limited Precision Points

abstract:
  Let X be a set of s points whose coordinates are known with only limited From
the numerical point of view, given a set X of s real points whose coordinates
are known with only limited precision, each set X* of real points whose
elements differ from those of X of a quantity less than the data uncertainty
can be considered equivalent to X. We present an algorithm that, given X and a
tolerance Tol on the data error, computes a set G of polynomials such that each
element of G "almost vanishing" at X and at all its equivalent sets X*. Even if
G is not, in the general case, a basis of the vanishing ideal I(X), we show
that, differently from the basis of I(X) that can be greatly influenced by the
data uncertainty, G can determine a geometrical configuration simultaneously
characterizing the set X and all its equivalent sets X*.


title:
Multiparticle production in the mean field approximation of high density
  QCD

abstract:
  The generating functional is suggested for multiparticle generation
processes. In mean field approximation of high density QCD two equations for
new generating functional are derived: linear functional equation for an
arbitrary initial condition and non-linear one for a specific initial
condition. The non-linear equation has the form of Kovchegov-Levin equation for
diffraction production and gives its generalization on the processes with fixed
multiplicities of produced particles.


title: First supernovae in dwarf protogalaxies

abstract:
  (Abridged) We explore numerically the chemical, thermal, and dynamical
evolution of a shell formed by a high-energy supernova explosion ($10^{53}$
erg) in dwarf protogalaxies with total mass $10^7 M_\odot$ at a redshift
$z=12$. We consider two initial configurations for the baryonic matter, one
without rotation and the other having the ratio of rotational to gravitational
energy $\beta=0.17$. The (non-rotating) dark matter halo is described by a
quasi-isothermal sphere. We find that the dynamics of the shell is different in
protogalaxies with and without rotation. For instance, the Rayleigh-Taylor
instability in the shell develops faster in protogalaxies without rotation. The
fraction of a blown-away baryonic mass is approximately twice as large in
models with rotation ($\sim 20%$) than in models without rotation. On the other
hand, the chemical evolution of gas in protogalaxies with and without rotation
is found to be similar. The relative number densities of molecular hydrogen and
HD molecules in the cold gas ($T \le 10^3$ K) saturate at typical values of
$10^{-3}$ and $10^{-7}$, respectively. The clumps formed in the fragmented
shell move with velocities that are at least twice as large as the escape
velocity. The mass of the clumps is $\sim 0.1-10 \msun$, which is lower than
the Jeans mass. We conclude that the clumps are pressure supported. A supernova
explosion with energy $10^{53}$ ergs destructs our model protogalaxy. The
clumps formed in the fragmented shell are pressure supported. We conclude that
protogalaxies with total mass $\sim 10^{7} M_\odot$ are unlikely to form stars
due to high-energy supernova explosions of the first stars.


title: On the spectral gap of the Kac walk and other binary collision processes

abstract:
  We give a new and elementary computation of the spectral gap of the Kac walk
on the N-sphere. The result is obtained as a by-product of a more general
observation which allows to reduce the analysis of the spectral gap of an
N-component system to that of the same system for N=3. The method applies to a
number of random 'binary collision' processes with complete-graph structure,
including non-homogeneous examples such as exclusion and colored exclusion
processes with site disorder.


title: Modeling temporal fluctuations in avalanching systems

abstract:
  We demonstrate how to model the toppling activity in avalanching systems by
stochastic differential equations (SDEs). The theory is developed as a
generalization of the classical mean field approach to sandpile dynamics by
formulating it as a generalization of Itoh's SDE. This equation contains a
fractional Gaussian noise term representing the branching of an avalanche into
small active clusters, and a drift term reflecting the tendency for small
avalanches to grow and large avalanches to be constricted by the finite system
size. If one defines avalanching to take place when the toppling activity
exceeds a certain threshold the stochastic model allows us to compute the
avalanche exponents in the continum limit as functions of the Hurst exponent of
the noise. The results are found to agree well with numerical simulations in
the Bak-Tang-Wiesenfeld and Zhang sandpile models. The stochastic model also
provides a method for computing the probability density functions of the
fluctuations in the toppling activity itself. We show that the sandpiles do not
belong to the class of phenomena giving rise to universal non-Gaussian
probability density functions for the global activity. Moreover, we demonstrate
essential differences between the fluctuations of total kinetic energy in a
two-dimensional turbulence simulation and the toppling activity in sandpiles.


title: Low-temperature primordial gas in merging halos

abstract:
  Thermal regime of the baryons behind shock waves arising in the process of
virialization of dark matter halos is governed at cetrain conditions by
radiation of HD lines. A small fraction of the shocked gas can cool down to the
temperature of the cosmic microwave background (CMB). We estimate an upper
limit for this fraction: at $z=10$ it increases sharply from about $q_{_T}\sim
10^{-3}$ for dark halos of $M=5\times 10^7\msun$ to $\sim 0.1$ for halos with
$M=10^8\msun$. Further increase of the halo mass does not lead however to a
significant growth of $q_T$ -- the asymptotic value for $M\gg 10^8\msun$ is of
0.3. We estimate star formation rate associated with such shock waves, and show
that they can provide a small but not negligible fraction of the star
formation. We argue that extremely metal-poor low-mass stars in the Milky Way
may have been formed from primordial gas behind such shocks.


title: Collective neutrinos oscillation in matter and CP-violation

abstract:
  We explore CP violation effects on the neutrino propagation in dense
environments, such as in core-collapse supernovae, where the neutrino
self-interaction induces non-linear evolution equations. We demonstrate that
the electron (anti)neutrino fluxes are not sensitive to the CP violating phase
if the muon and tau neutrinos interact similarly with matter. On the other
hand, we numerically show that new features arise, because of the non-linearity
and the flux dependence of the evolution equations, when the muon and tau
neutrinos have different fluxes at the neutrinosphere (due to loop corrections
or of physics beyond the Standard Model). In particular, the electron
(anti)neutrino probabilities and fluxes depend upon the CP violating phase. We
also discuss the CP effects induced by radiative corrections to the neutrino
refractive index.


title: A Berger type normal holonomy theorem for complex submanifolds

abstract:
  We prove a Berger type theorem for the normal holonomy group (i.e., the
holonomy group of the normal connection) of a full complete complex submanifold
of the complex projective space. Namely, if the normal holonomy does not act
transitively, then the submanifold is the complex orbit, in the complex
projective space, of the isotropy representation of an irreducible Hermitian
symmetric space of rank greater or equal to 3. Moreover, we show that for
complete irreducible complex submanifolds of the complex Euclidean space the
normal holonomy is generic, i.e., it acts transitively on the unit sphere of
the normal space. The methods in the proofs rely heavily on the singular data
of appropriate holonomy tubes (after lifting the submanifold to the complex
Euclidean space, in the projective case) and basic facts of complex
submanifolds.


title: Low-temperature thermopower study of YbRh2Si2

abstract:
  The heavy-fermion compound YbRh2Si2 exhibits an antiferromagnetic (AFM) phase
transition at an extremely low temperature of TN = 70 mK. Upon applying a tiny
magnetic field of Bc = 60 mT the AFM ordering is suppressed and the system is
driven toward a field-induced quantum critical point (QCP). Here, we present
low-temperature thermopower S(T) measurements of high-quality YbRh2Si2 single
crystals down to 30 mK. S(T) is found negative with comparably large values in
the paramagnetic state. In zero field no Landau-Fermi-liquid (LFL) like
behavior is observed within the magnetically ordered phase. However, a sign
change from negative to positive appears at lowest temperatures on the magnetic
side of the QCP. For higher fields B > Bc a linear extrapolation of S to zero
clearly evidences the recovery of LFL regime. The crossover temperature is
sharply determined and coincides perfectly with the one derived from
resistivity and specific heat investigations.


title: The WITCH experiment: Acquiring the first recoil ion spectrum

abstract:
  The standard model of the electroweak interaction describes beta-decay in the
well-known V-A form. Nevertheless, the most general Hamiltonian of a beta-decay
includes also other possible interaction types, e.g. scalar (S) and tensor (T)
contributions, which are not fully ruled out yet experimentally. The WITCH
experiment aims to study a possible admixture of these exotic interaction types
in nuclear beta-decay by a precise measurement of the shape of the recoil ion
energy spectrum. The experimental set-up couples a double Penning trap system
and a retardation spectrometer. The set-up is installed in ISOLDE/CERN and was
recently shown to be fully operational. The current status of the experiment is
presented together with the data acquired during the 2006 campaign, showing the
first recoil ion energy spectrum obtained. The data taking procedure and
corresponding data acquisition system are described in more detail. Several
further technical improvements are briefly reviewed.


title:
Elastic properties and chemical bonding in ternary arsenide SrFe2As2 and
  quaternary oxyarsenide LaFeAsO - basic phases for new 38-55K superconductors

abstract:
  We report the first-principle FLAPW-GGA calculations of the elastic
properties of two related layered phases, namely, the ternary arsenide SrFe2As2
and the quaternary oxyarsenide LaFeAsO - basic phases for the newly discovered
"122" and "1111" 38-55K superconductors. The independent elastic constants
(Cij), bulk moduli, compressibility, and shear moduli are evaluated and
discussed. The numerical estimates of the elastic parameters of the
polycrystalline SrFe2As2 and LaFeAsO ceramics are performed for the first time.
Additionally, the peculiarities of chemical bonding in these phases are
discussed.


title: Elastic-Net Regularization in Learning Theory

abstract:
  Within the framework of statistical learning theory we analyze in detail the
so-called elastic-net regularization scheme proposed by Zou and Hastie for the
selection of groups of correlated variables. To investigate on the statistical
properties of this scheme and in particular on its consistency properties, we
set up a suitable mathematical framework. Our setting is random-design
regression where we allow the response variable to be vector-valued and we
consider prediction functions which are linear combination of elements ({\em
features}) in an infinite-dimensional dictionary. Under the assumption that the
regression function admits a sparse representation on the dictionary, we prove
that there exists a particular ``{\em elastic-net representation}'' of the
regression function such that, if the number of data increases, the elastic-net
estimator is consistent not only for prediction but also for variable/feature
selection. Our results include finite-sample bounds and an adaptive scheme to
select the regularization parameter. Moreover, using convex analysis tools, we
derive an iterative thresholding algorithm for computing the elastic-net
solution which is different from the optimization procedure originally proposed
by Zou and Hastie


title: Suppression of spin-state transition in epitaxially strained LaCoO_{3}

abstract:
  Epitaxial thin films of LaCoO_{3} (E-LCO) exhibit ferromagnetic order with a
transition temperature T_c = 85 K, while polycrystalline thin LaCoO_{3} films
(P-LCO) remain paramagnetic. The temperature-dependent spin-state structure for
both E-LCO and P-LCO was studied by x-ray absorption spectroscopy at the Co
L_{2,3} and O K edges. Considerable spectral redistributions over temperature
are observed for P-LCO. The spectra for E-LCO, on the other hand, do not show
any significant changes for temperatures between 30 K and 450 K at both edges,
indicating that the spin state remains constant and that the epitaxial strain
inhibits any population of the low-spin (S = 0) state with decreasing
temperature. This observation identifies an important prerequisite for
ferromagnetism in E-LCO thin films.


title: Transport through quantum dots with magnetic impurities

abstract:
  We analyze the electronic transport through a quantum dot that contains a
magnetic impurity. The coherent transport of electrons is governed by the
quantum confinement inside the dot, but is also influenced by the exchange
interaction with the impurity. The interplay between the two gives raise to the
singlet-triplet splitting of the energy levels available for the tunneling
electron. In this paper, we focus on the charge fluctuations and, more
precisely, the height of the conductance peaks. We show that the conductance
peaks corresponding to the triplet levels are three times higher than those
corresponding to singlet levels, if electronic correlations are neglected (for
non-interacting dots, when an exact solution can be obtained). Next, we
consider the Coulomb repulsion and the many-body correlations. In this case,
the singlet/triplet peak height ratio has a complex behavior. Usually the
highest peak corresponds to the state that is lowest in energy (ground state),
regardless if it is singlet or triplet. In the end, we get an insight on the
Kondo regime for such a system, and show the formation of three Kondo peaks. We
use the equation of motion method with appropriate decoupling.


title:
Stress Development and Impurity Segregation during Oxidation of the
  Si(100) Surface

abstract:
  We have studied the segregation of P and B impurities during oxidation of the
Si(100) surface by means of combined static and dynamical first-principles
simulations based on density functional theory. In the bare surface, dopants
segregate to chemically stable surface sites or to locally compressed
subsurface sites. Surface oxidation is accompanied by development of tensile
surface stress up to 2.9 N/m at a coverage of 1.5 monolayers of oxygen and by
formation of oxidised Si species with charges increasing approximately linearly
with the number of neighbouring oxygen atoms. Substitutional P and B defects
are energetically unstable within the native oxide layer, and are
preferentially located at or beneath the Si/SiOx interface. Consistently,
first-principles molecular dynamics simulations of native oxide formation on
doped surfaces reveal that dopants avoid the formation of P-O and B-O bonds,
suggesting a surface oxidation mechanism whereby impurities remain trapped at
the Si/SiOx interface. This seems to preclude a direct influence of impurities
on the surface electrostatics and, hence, on the interactions with an external
environment.


title: A characterization of 2-player mechanisms for scheduling

abstract:
  We study the mechanism design problem of scheduling unrelated machines and we
completely characterize the decisive truthful mechanisms for two players when
the domain contains both positive and negative values. We show that the class
of truthful mechanisms is very limited: A decisive truthful mechanism
partitions the tasks into groups so that the tasks in each group are allocated
independently of the other groups. Tasks in a group of size at least two are
allocated by an affine minimizer and tasks in singleton groups by a
task-independent mechanism. This characterization is about all truthful
mechanisms, including those with unbounded approximation ratio.
  A direct consequence of this approach is that the approximation ratio of
mechanisms for two players is 2, even for two tasks. In fact, it follows that
for two players, VCG is the unique algorithm with optimal approximation 2.
  This characterization provides some support that any decisive truthful
mechanism (for 3 or more players) partitions the tasks into groups some of
which are allocated by affine minimizers, while the rest are allocated by a
threshold mechanism (in which a task is allocated to a player when it is below
a threshold value which depends only on the values of the other players). We
also show here that the class of threshold mechanisms is identical to the class
of additive mechanisms.


title: Bremsstrahlung during $\alpha$-decay: quantum multipolar model

abstract:
  In this paper the improved multipolar model of bremsstrahlung accompanied the
$\alpha$-decay is presented. The angular formalism of calculations of the
matrix elements, being enough complicated component of the model, is stated in
details. A new definition of the angular (differential) probability of the
photon emission in the $\alpha$-decay is proposed where direction of motion of
the $\alpha$-particle outside (with its tunneling inside barrier) is defined on
the basis of angular distribution of its spacial wave function. In such
approach, the model gives values of the angular probability of the photons
emission in absolute scale, without its normalization on experimental data.
Effectiveness of the proposed definition and accuracy of the spectra
calculations of the bremsstrahlung spectra are analyzed in their comparison
with experimental data for the $^{210}{\rm Po}$, $^{214}{\rm Po}$, $^{226}{\rm
Ra}$ and $^{244}{\rm Cm}$ nuclei, and for some other nuclei predictions are
performed (in absolute scale). With a purpose to find characteristics taking
influence on the bremsstrahlung probability strongly, a dependence of the
bremsstrahlung probability on effective charge of the decaying system is
analyzed. As a natural result, as supposed type of decaying system the emission
of proton from nucleus is studied, for which the effective charge is
essentially larger in a comparison with $\alpha$-decay. For some proton
emitters estimations of the bremsstrahlung probability are obtained (at first
time, in fully quantum approach). Also the bremsstrahlung in fission of the
$^{252}{\rm Cf}$ nucleus is analyzed.


title: Dark Matter Signatures in the Anisotropic Radio Sky

abstract:
  We calculate intensity and angular power spectrum of the cosmological
background of synchrotron emission from cold dark matter annihilations into
electron positron pairs. We compare this background with intensity and
anisotropy of astrophysical and cosmological radio backgrounds, such as from
normal galaxies, radio-galaxies, galaxy cluster accretion shocks, the cosmic
microwave background and with Galactic foregrounds. Under modest assumptions
for the dark matter clustering we find that around 2 GHz average intensity and
fluctuations of the radio background at sub-degree scales allows to probe dark
matter masses >100 GeV and annihilation cross sections not far from the natural
values <sigma v> ~ 3 x 10^(-26) cm^3/s required to reproduce the correct relic
density of thermal dark matter. The angular power spectrum of the signal from
dark matter annihilation tends to be flatter than that from astrophysical radio
backgrounds. Furthermore, radio source counts have comparable constraining
power. Such signatures are interesting especially for future radio detectors
such as SKA.


title:
Modelling the onset of oxide formation on metal surfaces from first
  principles

abstract:
  The formation of ultrathin oxide layers on metal surfaces is a
non-thermally-activated process which takes place spontaneously at very low
temperatures within nanoseconds. This paper reports mechanistic details of the
initial oxidation of bare metal surfaces, in particular Al(111) and TiN(001),
as obtained by means of first-principles molecular dynamics modelling within
the Density-Functional Theory. It is shown that the reactions of bare metal
surfaces with O2 molecules take place according to a 'hot-atom' dissociative
mechanism which is triggered by the filling of the sigma-star antibonding
molecular orbital and is characterised by a sudden release of a large amount of
kinetic energy. This released energy provides a driving force for metal/oxygen
place-exchange processes which are responsible for the onset of oxide formation
at virtually 0 K and at oxygen coverages well below 1 monolayer (ML). Further
simulations of the oxidation reactions reveal that a disordered ultrathin oxide
forms on Al(111), whereas a rather ordered structure develops on TiN(001)
following a selective oxidation process which leaves clusters of Ti vacancies
in the TiN lattice underneath the oxide layer.


title:
Influence of an inter-chain coupling on spiral ground-state correlations
  in frustrated spin-1/2 J1-J2 Heisenberg chains

abstract:
  We investigate the influence of an inter-chain coupling on the spiral ground
state correlations of a spin-1/2 Heisenberg model consisting of a
two-dimensional array of coupled chains with nearest (J1) and frustrating
next-nearest neighbor (J2) in-chain exchange couplings. Using the
coupled-cluster method we calculate the transition point between the
commensurate and the incommensurate (spiral) ground state as well as the
quantum pitch angle of the spiral ground state. In addition, we provide a
simple empirical formula which describes the relation between the quantum pitch
angle and the frustration parameter J2/J1.


title: Dynamics of kicked matter-wave solitons in an optical lattice

abstract:
  We investigate effects of the application of a kick to one-dimensional
matter-wave solitons in a self-attractive Bose-Einstein condensate trapped in a
optical lattice. The resulting soliton's dynamics is studied within the
framework of the time-dependent nonpolynomial Schrodinger equation. The
crossover from the pinning to quasi-free motion crucially depends on the size
of the kick, strength of the self-attraction, and parameters of the optical
lattice.


title:
Do metals exist in two dimensions? A study of many-body localisation in
  low density electron gas

abstract:
  Using a combination of ground state quantum Monte-Carlo and finite size
scaling techniques, we perform a systematic study of the effect of Coulomb
interaction on the localisation length of a disordered two-dimensional electron
gas. We find that correlations delocalise the 2D system. In the absence of
valley degeneracy (as in GaAs heterostructures), this delocalization effect
corresponds to a finite increase of the localization length. The delocalisation
is much more dramatic in the presence of valley degeneracy (as in Si MOSFETSs)
where the localization length increases drastically. Our results suggest that a
rather simple mechanism can account for the main features of the metallic
behaviour observed in high mobility Si MOSFETs. Our findings support the claim
that this behaviour is indeed a genuine effect of the presence of
electron-electron interactions, yet that the system is not a ``true'' metal in
the thermodynamic sense.


title: On the material time derivative of volume, surface, and line integrals

abstract:
  Traditional derivation of the material time derivative of volume, surface,
and line integrals relies upon the notion of a referential configuration of
continuum. Such a notion, however, is artificial and, probably, somewhat
misleading in cases of liquids, gases, plastic flow of solids etc. It is,
consequently, desirable to separate the formal calculation of the material time
derivative of time-dependent integrals from any physics that can be related
with them. Such a separation is targeted in the present letter where no
referential continuum configuration or other physical notion is involved. The
material time derivative of volume, surface, and line integrals is presented as
a purely mathematical manipulation.


title:
Pair correlations of scattered atoms from two colliding Bose-Einstein
  Condensates: Perturbative Approach

abstract:
  We apply an analytical model for anisotropic, colliding Bose-Einstein
condensates in a spontaneous four wave mixing geometry to evaluate the second
order correlation function of the field of scattered atoms. Our approach uses
quantized scattering modes and the equivalent of a classical, undepleted pump
approximation. Results to lowest order in perturbation theory are compared with
a recent experiment and with other theoretical approaches.


title:
Exact asymptotics for non-radiative migration-accelerated energy
  transfer in one-dimensional systems

abstract:
  We study direct energy transfer by multipolar or exchange interactions
between diffusive excited donor and diffusive unexcited acceptors. Extending
over the case of long-range transfer of an excitation energy a non-perturbative
approach by Bray and Blythe [Phys. Rev. Lett. 89, 150601 (2002)], originally
developed for contact diffusion-controlled reactions, we determine exactly
long-time asymptotics of the donor decay function in one-dimensional systems.


title:
Quantum Homodyne Tomography as an Informationally Complete Positive
  Operator Valued Measure

abstract:
  We define a positive operator valued measure $E$ on $[0,2\pi]\times R$
describing the measurement of randomly sampled quadratures in quantum homodyne
tomography, and we study its probabilistic properties. Moreover, we give a
mathematical analysis of the relation between the description of a state in
terms of $E$ and the description provided by its Wigner transform.


title: Minimal Seesaw Textures with Two Heavy Neutrinos

abstract:
  We systematically analyze the Dirac and the Majorana mass matrices in seesaw
models with two heavy right-handed neutrinos. We perform thorough
classification of the vanishing matrix elements which are compatible with the
results from the current neutrino oscillation experiments. We include the
possibility of a non-diagonal Majorana mass matrix which leads to new solutions
viable with data. In a basis where the Majorana mass matrix is diagonal, these
solutions imply a Dirac matrix with specific relationships amongst its
elements. We find that at the level of total 4 zeros together in the Dirac and
the Majorana sectors, the mass matrices are almost consistent with the data but
one mixing angle is predicted to be unsuitable. At the next level, i.e. with
total 3 zeros, only seven patterns of mass matrices describe the experimental
data well. The seven solutions have testable predictions for the future
neutrino experiments. In particular, each solution has definite predictions
about the observation of the 1-3 leptonic mixing angle and the effective mass
measured in neutrino-less double beta decay. The solutions of the mass matrices
contain novel texture forms and provide new insights into the lepton-generation
structure. We also discuss possible connections between these textures and the
tri-bimaximal mixing to search for symmetry principles behind the mass matrix
structure.


title: Atmospheric refractivity effects on mid-infrared ELT adaptive optics

abstract:
  We discuss the effect of atmospheric dispersion on the performance of a
mid-infrared adaptive optics assisted instrument on an extremely large
telescope (ELT). Dispersion and atmospheric chromaticity is generally
considered to be negligible in this wavelength regime. It is shown here,
however, that with the much-reduced diffraction limit size on an ELT and the
need for diffraction-limited performance, refractivity phenomena should be
carefully considered in the design and operation of such an instrument. We
include an overview of the theory of refractivity, and the influence of
infrared resonances caused by the presence of water vapour and other
constituents in the atmosphere. `Traditional' atmospheric dispersion is likely
to cause a loss of Strehl only at the shortest wavelengths (L-band). A more
likely source of error is the difference in wavelengths at which the wavefront
is sensed and corrected, leading to pointing offsets between wavefront sensor
and science instrument that evolve with time over a long exposure. Infrared
radiation is also subject to additional turbulence caused by the presence of
water vapour in the atmosphere not seen by visible wavefront sensors, whose
effect is poorly understood. We make use of information obtained at radio
wavelengths to make a first-order estimate of its effect on the performance of
a mid-IR ground-based instrument. The calculations in this paper are performed
using parameters from two different sites, one `standard good site' and one
`high and dry site' to illustrate the importance of the choice of site for an
ELT.


title: Quantum Random Number Generator using Photon-Number Path Entanglement

abstract:
  We report a novel quantum random number generator based on the
photon-number$-$path entangled state which is prepared via two-photon quantum
interference at a beam splitter. The randomness in our scheme is of truly
quantum mechanical origin as it comes from the projection measurement of the
entangled two-photon state. The generated bit sequences satisfy the standard
randomness test.


title: Limit theorem for random walk in weakly dependent random scenery

abstract:
  Let $S=(S_k)_{k\geq 0}$ be a random walk on $\mathbb{Z}$ and
$\xi=(\xi_{i})_{i\in\mathbb{Z}}$ a stationary random sequence of centered
random variables, independent of $S$. We consider a random walk in random
scenery that is the sequence of random variables $(\Sigma_n)_{n\geq 0}$ where
$$\Sigma_n=\sum_{k=0}^n \xi_{S_k}, n\in\mathbb{N}.$$ Under a weak dependence
assumption on the scenery $\xi$ we prove a functional limit theorem
generalizing Kesten and Spitzer's theorem (1979).


title:
Implications to Sources of Ultra-high-energy Cosmic Rays from their
  Arrival Distribution

abstract:
  We estimate the local number density of sources of ultra-high-energy cosmic
rays (UHECRs) based on the statistical features of their arrival direction
distribution. We calculate the arrival distributions of protons above $10^{19}$
eV taking into account their propagation process in the Galactic magnetic field
and a structured intergalactic magnetic field, and statistically compare those
with the observational result of the Pierre Auger Observatory. The anisotropy
in the arrival distribution at the highest energies enables us to estimate the
number density of UHECR sources as $\sim 10^{-4} {\rm Mpc}^{-3}$ assuming the
persistent activity of UHECR sources. We compare the estimated number density
of UHECR sources with the number densities of known astrophysical objects. This
estimated number density is consistent with the number density of
Fanaroff-Reily I galaxies. We also discuss the reproducability of the observed
{\it isotropy} in the arrival distribution above $10^{19}$ eV. We find that the
estimated source model cannot reproduce the observed isotropy. However, the
observed isotropy can be reproduced with the number density of
$10^{-2}$-$10^{-3} {\rm Mpc}^{-3}$. This fact indicates the existence of UHECR
sources with a maximum acceleration energy of $\sim 10^{19}$ eV whose number
density is an order of magnitude more than that injecting the highest energy
cosmic rays.


title: Progress report on solar age calibration

abstract:
  We report on an ongoing investigation into a seismic calibration of solar
models designed for estimating the main-sequence age and a measure of the
chemical abundances of the Sun. Only modes of low degree are employed, so that
with appropriate modification the procedure could be applied to other stars. We
have found that, as has been anticipated, a separation of the contributions to
the seismic frequencies arising from the relatively smooth, glitch-free,
background structure of the star and from glitches produced by helium
ionization and the abrupt gradient change at the base of the convection zone
renders the procedure more robust than earlier calibrations that fitted only
raw frequencies to glitch-free asymptotics. As in the past, we use asymptotic
analysis to design seismic signatures that are, to the best of our ability,
contaminated as little as possible by those uncertain properties of the star
that are not directly associated with age and chemical composition. The
calibration itself, however, employs only numerically computed
eigenfrequencies. It is based on a linear perturbation from a reference model.
Two reference models have been used, one somewhat younger, the other somewhat
older than the Sun. The two calibrations, which use BiSON data, are
more-or-less consistent, and yield a main-sequence age $t_\odot=4.68\pm0.02
$Gy, coupled with a formal initial heavy-element abundance $Z=0.0169\pm0.0005$.
The error analysis has not yet been completed, so the estimated precision must
be taken with a pinch of salt.


title:
A Fortran 90 program to solve the Hartree-Fock equations for interacting
  spin-1/2 Fermions confined in Harmonic potentials

abstract:
  A set of weakly interacting spin-1/2 Fermions, confined by a harmonic
oscillator potential, and interacting with each other via a contact potential,
is a model system which closely represents the physics of a dilute gas of
two-component Fermionic atoms confined in a magneto-optic trap. In the present
work, our aim is to present a Fortran 90 computer program which, using a basis
set expansion technique, solves the Hartree-Fock (HF) equations for spin-1/2$
Fermions confined by a three-dimensional harmonic oscillator potential, and
interacting with each other via pair-wise delta-function potentials.
Additionally, the program can also account for those anharmonic potentials
which can be expressed as a polynomial in the position operators $x,$ $y$, and
$z$. Both the restricted-HF (RHF), and the unrestricted-HF (UHF) equations can
be solved for a given number of Fermions, with either repulsive or attractive
interactions among them. The option of UHF solutions for such systems also
allows us to study possible magnetic properties of the physics of two-component
confined atomic Fermi gases, with imbalanced populations. Using our code we
also demonstrate that such a system exhibits shell structure, and follows
Hund's rule.


title:
Delicate f(R) gravity models with disappearing cosmological constant and
  observational constraints on the model parameters

abstract:
  We study the $f(R)$ theory of gravity using metric approach. In particular we
investigate the recently proposed model by Hu-Sawicki, Appleby $-$ Battye and
Starobinsky. In this model, the cosmological constant is zero in flat space
time. The model passes both the Solar system and the laboratory tests. But the
model parameters need to be fine tuned to avoid the finite time singularity
recently pointed in the literature. We check the concordance of this model with
the $H(z)$ and baryon acoustic oscillation data. We find that the model
resembles the $\Lambda$CDM at high redshift. However, for some parameter values
there are variations in the expansion history of the universe at low redshift.


title: W and Anomalous Single Top Production at HERA

abstract:
  The analysis of $W$ production and the search for anomalous single top
production is performed with the H1 detector at HERA with an integrated
luminosity of 0.5 fb$^{-1}$, consisting of the complete high energy data from
the HERA programme. Production cross section measurements of single $W$
production, as well as $W$ polarisation fractions in events containing isolated
leptons and missing transverse momentum are also presented. In the context of a
search for single top production an upper limit on the top production cross
section $\sigma_{ep\to etX} < 0.16$ pb is established at the 95% confidence
level, corresponding to an upper bound on the anomalous magnetic coupling
$\kappa_{tu\gamma} < 0.14$.


title: The clustering of Ly-alpha emitters in a LambdaCDM Universe

abstract:
  We combine a semi-analytical model of galaxy formation with a very large
simulation which follows the growth of large scale structure in a LambdaCDM
universe to predict the clustering of Ly-alpha emitters. We find that the
clustering strength of Ly-alpha emitters has only a weak dependence on Ly-alpha
luminosity but a strong dependence on redshift. With increasing redshift,
Ly-alpha emitters trace progressively rarer, higher density regions of the
universe. Due to the large volume of the simulation, over 100 times bigger than
any previously used for this application, we can construct mock catalogues of
Ly-alpha emitters and study the sample variance of current and forthcoming
surveys. We find that the number and clustering of Ly-alpha emitters in our
mock catalogues are in agreement with measurements from current surveys, but
that there is a considerable scatter in these quantities. We argue that a
proposed survey of emitters at z=8.8 should be extended significantly in solid
angle to allow a robust measurement of Ly-alpha emitter clustering.


title:
Diffraction Gratings for Neutrons from Polymers and Holographic
  Polymer-Dispersed Liquid Crystals

abstract:
  We discuss the applicability of holographically recorded gratings in
photopolymers and holographic polymer-dispersed liquid crystals as neutron
optical elements. An experimental investigation of their properties for light
and neutrons with different grating spacings and grating thicknesses is
performed. The angular dependencies of the diffraction efficiencies for those
gratings are interpreted in terms of a rigourous coupled wave analysis.
Starting from the obtained results we work out the lines for the production of
an optimised neutron optical diffraction grating, i.e., high diffraction
efficiency in the Bragg diffraction regime with moderate angular selectivity.


title:
Investigation of stimulated dynamics in strongly anisotropic
  high-temperature superconductors system Bi-Pb-Sr-Ca-Cu-O

abstract:
  It is used the mechanical method of Abrikosov vortex stimulated dynamics
investigation in superconductors. With its help it was studied relaxation
phenomena in vortex matter of high-temperature superconductors. It established
that pulsed magnetic fields change the course of relaxation processes taking
place in vortex matter. The study of the influence of magnetic pulses differing
by their durations and amplitudes on vortex system of strongly anisotropic
high-temperature superconductors system Bi1.7Pb0.3Sr2Ca2Cu3O10-d showed the
presence of threshold phenomena. The small duration pulses do not change the
course of relaxation processes taking place in vortex matter. When the duration
of pulses exceeds some critical value (threshold), then their influence change
the course of relaxation process which is revealed by stepwise change of
relaxing mechanical moment.. These investigation showed that the time for
formatting of Abrikosov vortex lattice in Bi1.7Pb0.3Sr2Ca2Cu3O10-d is of the
order of 150 us which on the order of value exceeds the time necessary for
formation of a single vortex observed in isotropic high-temperature
superconductor HoBa2Cu3O7-d and on two orders exceeds the creation time of a
single vortex observed in classical type II superconductors.


title:
Three different routes from the directed Ising to the directed
  percolation class

abstract:
  Scaling nature of absorbing critical phenomena is well understood for the
directed percolation (DP) and the directed Ising (DI) systems. However, a full
analysis of the crossover behavior is still lacking, which is of our interest
in this study. There are three different routes from the DI to the DP classes
by introducing a symmetry breaking field (SB), breaking a modulo 2 conservation
(CB), or making channels connecting two equivalent absorbing states (CC). Each
route can be characterized by a crossover exponent, which is found numerically
as $\phi=2.1\pm 0.1$ (SB), $4.6\pm 0.2$ (CB), and $2.9\pm 0.1$ (CC),
respectively. The difference between the SB and CB crossover can be understood
easily in the domain wall language, while the CC crossover involves an
additional critical singularity in the auxiliary field density with the memory
effect to identify itself independent.


title: A Non-Termination Criterion for Binary Constraint Logic Programs

abstract:
  On the one hand, termination analysis of logic programs is now a fairly
established research topic within the logic programming community. On the other
hand, non-termination analysis seems to remain a much less attractive subject.
If we divide this line of research into two kinds of approaches: dynamic versus
static analysis, this paper belongs to the latter. It proposes a criterion for
detecting non-terminating atomic queries with respect to binary CLP rules,
which strictly generalizes our previous works on this subject. We give a
generic operational definition and an implemented logical form of this
criterion. Then we show that the logical form is correct and complete with
respect to the operational definition.


title:
Dichotomy results for delay differential equations with negative
  Schwarzian

abstract:
  We gain further insight into the use of the Schwarzian derivative to obtain
new results for a family of functional differential equations including the
famous Wright's equation and the Mackey-Glass type delay differential
equations. We present some dichotomy results, which allow us to get easily
computable bounds of the global attractor. We also discuss related conjectures,
and formulate new open problems.


title: The One-Loop H^2R^3 and H^2(DH)^2R Terms in the Effective Action

abstract:
  We consider the one-loop B^2h^3 and B^4h amplitudes in type II string theory,
where B is the NS-NS two-form and h the graviton, and expand to lowest order in
alpha'. After subtracting diagrams due to quartic terms in the effective
action, we determine the presence and structure of both an H^2R^3 and
H^2(DH)^2R term. We show that both terms are multiplied by the usual
(t_8t_8\pm{1/8}\epsilon_{10}\epsilon_{10}) factor.


title: Variational Principle Involving the Stress Tensor in Elastodynamics

abstract:
  In the mechanics of inviscid conservative fluids, it is classical to generate
the equations of dynamics by formulating with adequate variables, that the
pressure integral calculated in the time-space domain corresponding to the
motion of the continuous medium is stationary. The present study extends this
principle to the dynamics of large deformations for isentropic motions in
thermo-elastic bodies: we use a new way of writing the equations of motion in
terms of potentials and we substitute the trace of the stress tensor for the
pressure term.


title:
Noise induced dynamics in adaptive networks with applications to
  epidemiology

abstract:
  Recent work in modeling the coupling between disease dynamics and dynamic
social network geometry has led to the examination of how human interactions
force a rewiring of connections in a population. Rewiring of the network may be
considered an adaptive response to social forces due to disease spread, which
in turn feeds back to the disease dynamics. Such epidemic models, called
adaptive networks, have led to new dynamical instabilities along with the
creation of multiple attracting states. The co-existence of several attractors
is sensitive to internal and external fluctuations, and leads to enhanced
stochastic oscillatory outbreaks and disease extinction. The aim of this paper
is to explore the bifurcations of adaptive network models in the presence of
fluctuations and to review some of the new fluctuation phenomena induced in
adaptive networks.


title: Description of the fluctuating colloid-polymer interface

abstract:
  To describe the full spectrum of surface fluctuations of the interface
between phase-separated colloid-polymer mixtures from low scattering vector q
(classical capillary wave theory) to high q (bulk-like fluctuations), one must
take account of the interface's bending rigidity. We find that the bending
rigidity is negative and that on approach to the critical point it vanishes
proportionally to the interfacial tension. Both features are in agreement with
Monte Carlo simulations.


title: Oscillations of rapidly rotating stratified neutron stars

abstract:
  We use time-evolutions of the linear perturbation equations to study the
oscillations of rapidly rotating neutrons stars. Our models account for the
buoyancy due to composition gradients and we study, for the first time, the
nature of the resultant g-modes in a fast spinning star. We provide detailed
comparisons of non-stratified and stratified models. This leads to an improved
understanding of the relationship between the inertial modes of a
non-stratified star and the g-modes of a stratified system. In particular, we
demonstrate that each g-mode becomes rotation-dominated, i.e. approaches a
particular inertial mode, as the rotation rate of the star is increased. We
also discuss issues relating to the gravitational-wave driven instability of
the various classes of oscillation modes.


title:
The behavior of subluminous X-ray transients near the Galactic center as
  observed using the X-ray telescope aboard Swift

abstract:
  In this paper we report on the spectral analysis of seven X-ray transients,
which were found to be active during a monitoring campaign of the Galactic
center carried out in 2006 and 2007 using the X-ray telescope aboard the Swift
satellite. This campaign detected new outbursts of five known X-ray transients
and discovered two new systems. Their 2-10 keV peak luminosities range from
1E34 to 6E36 erg/s. Two of the sources discussed in this paper are confirmed
neutron star systems (AX J1745.6-2901 and GRS 1741-2853), while the five others
have an unknown nature. We discuss the characteristics of the observed
outbursts and the duty cycles of the various systems. Several of the detected
transients seem to undergo enhanced X-ray activity with levels intermediate
between quiescence and full outburst. We discuss the possibility that the
subluminous appearance of the eclipsing X-ray burster AX J1745.6-2901 is due to
line-of-sight effects. We detected two type-I X-ray bursts with a duration of
50-60 seconds from AX J1745.6-2901, which we discuss in view of the bursting
behavior of low-luminosity X-ray transients. Assuming that we are dealing with
accreting neutron stars and black holes, we estimate the time-average accretion
rate, Mdot, of the transients, which is an important input parameter for binary
evolution models that attempt to explain the nature of subluminous X-ray
transients. Our estimates lie in the range of 3E-13 Msun/yr < Mdot < 1E-10
Msun/yr, if the systems are neutron star X-ray binaries and between 4E-14
Msun/yr < Mdot < 2E-11 Msun/yr for a scenario where the accreting object is a
black hole. Some of the systems have such low estimated mass-accretion rates
that they possibly pose a challenge for binary evolution models.


title:
On Fermi acceleration and MHD-instabilities at ultra-relativistic
  magnetized shock waves

abstract:
  Fermi acceleration can take place at ultra-relativistic shock waves if the
upstream or downstream magnetic field has been remodeled so that most of the
magnetic power lies on short spatial scales. The relevant conditions under
which Fermi acceleration become efficient in the presence of both a coherent
and a short scale turbulent magnetic field are addressed. Within the MHD
approximation, this paper then studies the amplification of a pre-existing
magnetic field through the streaming of cosmic rays upstream of a relativistic
shock wave. The magnetic field is assumed to be perpendicular in the shock
front frame, as generally expected in the limit of large shock Lorentz factor.
In the MHD regime, compressive instabilities seeded by the net cosmic-ray
charge in the shock precursor (as seen in the shock front frame) develop on the
shortest spatial scales but saturate at a moderate level deltaB/B ~ 1, which is
not sufficient for Fermi acceleration. As we argue, it is possible that other
instabilities outside the MHD range provide enough amplification to allow
successful Fermi acceleration.


title:
Time-Resolved characterization of InAsP/InP quantum dots emitting in the
  C-band telecommunication window

abstract:
  The dynamic response of InAsP quantum dots grown on InP(001) substrates by
low-pressure Metalorganic Vapor Phase Epitaxy emitting around 1.55 $\mu$m, is
investigated by means of time-resolved microphotoluminescence as a function of
temperature. Exciton lifetime steadily increases from 1 ns at low temperature
to reach 4 ns at 300K while the integrated photoluminescence intensity
decreases only by a factor of 2/3. These characteristics give evidence that
such InAsP/InP quantum dots provide a strong carrier confinement even at room
temperature and that their dynamic response is not affected by thermally
activated non-radiative recombination up to room temperature.


title:
A simple proof that any additive basis has only finitely many essential
  subsets

abstract:
  Let $A$ be an additive basis. We call ``essential subset'' of $A$ any finite
subset $P$ of $A$ such that $A \setminus P$ is not an additive basis and that
$P$ is minimal (for the inclusion order) to have this property. A recent
theorem due to B. Deschamps and the author states that any additive basis has
only finitely many essential subsets (see ``Essentialit\'e dans les bases
additives, J. Number Theory, 123 (2007), p. 170-192''). The aim of this note is
to give a simple proof of this theorem.


title:
A stochastic SIR model with contact-tracing: large population limits and
  statistical inference

abstract:
  A stochastic epidemic model accounting for the effect of contact-tracing on
the spread of an infectious disease is studied. Precisely, individuals
identified as infected may contribute to detecting other infectious individuals
by providing information related to persons with whom they have had possibly
infectious contacts. The population evolves through demographic, infection and
detection processes, in a way that its temporal evolution is described by a
stochastic Markov process, of which the component accounting for the
contact-tracing feature is assumed to be valued in a space of point measures.
For adequate scalings of the demographic, infection and detection rates, it is
shown to converge to the weak deterministic solution of a PDE system, as a
parameter n, interpreted as the population size roughly speaking, becomes
large. From the perspective of the analysis of infectious disease data, this
approximation result may serve as a key tool for exploring the asymptotic
properties of standard inference methods such as maximum likelihood estimation.
We state preliminary statistical results in this context. Eventually, relation
of the model to the available data of the HIV epidemic in Cuba, in which
country a contact-tracing detection system has been set up since 1986, is
investigated and numerical applications are carried out.


title:
Finite temperature and confinement along the extra dimensions studied on
  a five-dimensional U(1) lattice gauge model

abstract:
  In this paper we study the properties of the phase diagram of a simple extra
dimensional model on the lattice at finite temperature. We consider the
five-dimensional pure gauge abelian model with anisotropic couplings which at
zero temperature exhibits a new interesting phase, the layer phase. This phase
is characterized by a massless photon living on the four dimensional subspace
and confinement along the extra dimension. We show that, as long as the
temperature takes a non zero value the aforementioned layer phase disappears.
It would be equivalent to assume that at finite temperature the
higher-dimensional lattice model loses any feature of the layered structure due
to the deconfinement which opens up the interactions between the
three-dimensional subspaces at finite temperature.


title:
Joint analysis and estimation of stock prices and trading volume in
  Barndorff-Nielsen and Shephard stochastic volatility models

abstract:
  We introduce a variant of the Barndorff-Nielsen and Shephard stochastic
volatility model where the non Gaussian Ornstein-Uhlenbeck process describes
some measure of trading intensity like trading volume or number of trades
instead of unobservable instantaneous variance. We develop an explicit
estimator based on martingale estimating functions in a bivariate model that is
not a diffusion, but admits jumps. It is assumed that both the quantities are
observed on a discrete grid of fixed width, and the observation horizon tends
to infinity. We show that the estimator is consistent and asymptotically normal
and give explicit expressions of the asymptotic covariance matrix. Our method
is illustrated by a finite sample experiment and a statistical analysis on the
International Business Machines Corporation (IBM) stock from the New York Stock
Exchange (NYSE) and the Microsoft Corporation (MSFT) stock from Nasdaq during a
history of five years.


title: The Cauchy Problem for Membranes

abstract:
  We show existence and uniqueness for timelike minimal submanifolds (world
volume of p-branes) in ambient Lorentz manifolds admitting a time function in a
neighborhood of the initial submanifold. The initial value formulation
introduced and the conditions imposed on the initial data are given in purely
geometric terms. Only an initial direction must be prescribed in order to
provide uniqueness for the geometric problem. The result covers non-compact
initial submanifolds of any codimension. By considering the angle of the
initial direction and vector fields normal to the initial submanifold with the
unit normal to the foliation given by the time function we obtain a
quantitative description of "distance" to the light cone. This description
makes it possible to treat initial data which are arbitrarily close to the
light cone. Imposing uniform assumptions give a lower bound for a notion of
"time of existence" depending only on geometric quantities involving the length
of timelike curves lying in the solution.


title:
Instantaneous oscillatory direction and phase for multivariate
  timeseries

abstract:
  This text describes a generalization of the analytic signal (Gabor, 1946)
approach for the definition of instantaneous amplitude and phase to the case of
multivariate signals. It was originally written as an appendix for another
paper, where the determination of the locally dominant oscillatory direction
(the instantaneous amplitude) described here is used as a preprocessing step
for another kind of data analysis. The text is reproduced in a 'standalone'
form because the procedure might prove useful in other contexts too, especially
for the purpose of phase synchronization analysis (Rosenblum et al., 1996)
between two (or more) multivariate sets of time series (Pascual-Marqui, 2007).


title: Quantum phase transitions in the interacting boson model

abstract:
  This review is focused on various properties of quantum phase transitions
(QPTs) in the Interacting Boson Model (IBM) of nuclear structure. The model in
its infinite-size limit exhibits shape-phase transitions between spherical,
deformed prolate, and deformed oblate forms of the ground state. Finite-size
precursors of such behavior are verified by robust variations of nuclear
properties (nuclear masses, excitation energies, transition probabilities for
low lying levels) across the chart of nuclides. Simultaneously, the model
serves as a theoretical laboratory for studying diverse general features of
QPTs in interacting many-body systems, which differ in many respects from
lattice models of solid-state physics. We outline the most important fields of
the present interest: (a) The coexistence of first- and second-order phase
transitions supports studies related to the microscopic origin of the QPT
phenomena. (b) The competing quantum phases are characterized by specific
dynamical symmetries and novel symmetry related approaches are developed to
describe also the transitional dynamical domains. (c) In some parameter
regions, the QPT-like behavior can be ascribed also to individual excited
states, which is linked to the thermodynamic and classical descriptions of the
system. (d) The model and its phase structure can be extended in many
directions: by separating proton and neutron excitations, considering
odd-fermion degrees of freedom or different particle-hole configurations, by
including other types of bosons, higher order interactions, and by imposing
external rotation. All these aspects of IBM phase transitions are relevant in
the interpretation of experimental data and important for a fundamental
understanding of the QPT phenomenon.


title:
Variational multiparticle-multihole configuration mixing method applied
  to pairing correlations in nuclei

abstract:
  Applying a variational multiparticle-multihole configuration mixing method
whose purpose is to include correlations beyond the mean field in a unified way
without particle number and Pauli principle violations, we investigate
pairing-like correlations in the ground states of $ ^{116}$Sn,$ ^{106}$Sn and $
^{100}$Sn. The same effective nucleon-nucleon interaction namely, the D1S
parameterization of the Gogny force is used to derive both the mean field and
correlation components of nuclear wave functions. Calculations are performed
using an axially symetric representation. The structure of correlated wave
functions, their convergence with respect to the number of particle-hole
excitations and the influence of correlations on single-particle level spectra
and occupation probabilities are analyzed and compared with results obtained
with the same two-body effective interaction from BCS, Hartree-Fock-Bogoliubov
and particle number projected after variation BCS approaches. Calculations of
nuclear radii and the first theoretical excited $0^+$ states are compared with
experimental data.


title:
Nonparametric estimation of the characteristic triplet of a discretely
  observed L\'evy process

abstract:
  Given a discrete time sample $X_1,... X_n$ from a L\'evy process
$X=(X_t)_{t\geq 0}$ of a finite jump activity, we study the problem of
nonparametric estimation of the characteristic triplet $(\gamma,\sigma^2,\rho)$
corresponding to the process $X.$ Based on Fourier inversion and kernel
smoothing, we propose estimators of $\gamma,\sigma^2$ and $\rho$ and study
their asymptotic behaviour. The obtained results include derivation of upper
bounds on the mean square error of the estimators of $\gamma$ and $\sigma^2$
and an upper bound on the mean integrated square error of an estimator of
$\rho.$


title: Inference with Discriminative Posterior

abstract:
  We study Bayesian discriminative inference given a model family $p(c,\x,
\theta)$ that is assumed to contain all our prior information but still known
to be incorrect. This falls in between "standard" Bayesian generative modeling
and Bayesian regression, where the margin $p(\x,\theta)$ is known to be
uninformative about $p(c|\x,\theta)$. We give an axiomatic proof that
discriminative posterior is consistent for conditional inference; using the
discriminative posterior is standard practice in classical Bayesian regression,
but we show that it is theoretically justified for model families of joint
densities as well. A practical benefit compared to Bayesian regression is that
the standard methods of handling missing values in generative modeling can be
extended into discriminative inference, which is useful if the amount of data
is small. Compared to standard generative modeling, discriminative posterior
results in better conditional inference if the model family is incorrect. If
the model family contains also the true model, the discriminative posterior
gives the same result as standard Bayesian generative modeling. Practical
computation is done with Markov chain Monte Carlo.


title:
Stability of the curvature perturbation in dark sectors' mutual
  interacting models

abstract:
  We consider perturbations in a cosmological model with a small coupling
between dark energy and dark matter. We prove that the stability of the
curvature perturbation depends on the type of coupling between dark sectors.
When the dark energy is of quintessence type, if the coupling is proportional
to the dark matter energy density, it will drive the instability in the
curvature perturbations; however if the coupling is proportional to the energy
density of dark energy, there is room for the stability in the curvature
perturbations. When the dark energy is of phantom type, the perturbations are
always stable, no matter whether the coupling is proportional to the one or the
other energy density.


title: Conformal Field Theory and Statistical Mechanics

abstract:
  The lectures provide a pedagogical introduction to the methods of CFT as
applied to two-dimensional critical behaviour.


title: Race for the Kerr field

abstract:
  Roy P. Kerr has discovered his celebrated metric 45 years ago, yet the
problem to find a generalization of the Schwarzschild metric for a rotating
mass was faced much earlier. Lense and Thirring, Bach, Andress, Akeley, Lewis,
van Stockum and others have tried to solve it or to find an approximative
solution at least. In particular Achilles Papapetrou, from 1952 to 1961 in
Berlin, was interested in an exact solution. He directed the author in the late
autumn of 1959 to work on the problem. Why did these pre-Kerr attempts fail?
Comments based on personal reminiscences and old notes.


title:
Tuck's incompressibility function: statistics for zeta zeros and
  eigenvalues

abstract:
  For any function that is real for real x, positivity of Tuck's function
Q(x)=D'^2(x)/(D'^2(x)-D"(x) D(x)) is a condition for the absence of the complex
zeros close to the real axis. Study of the probability distribution P(Q), for
D(x) with N zeros corresponding to eigenvalues of the Gaussian unitary ensemble
(GUE), supports Tuck's observation that large values of Q are very rare for the
Riemann zeros. P(Q) has singularities at Q=0, Q=1 and Q=N. The moments
(averages of Q^m) are much smaller for the GUE than for uncorrelated random
(Poisson-distributed) zeros. For the Poisson case, the large-N limit of P(Q)
can be expressed as an integral with infinitely many poles, whose accumulation,
requiring regularization with the Lerch transcendent, generates the singularity
at Q=1, while the large-Q decay is determined by the pole closest to the
origin. Determining the large-N limit of P(Q) for the GUE seems difficult.

categories: cond-mat.stat-mech cond-mat.mes-hall math-ph math.MP


title:
Coherent-incoherent transition in a Cooper-pair-box coupled to a quantum
  oscillator: an equilibrium approach

abstract:
  Temperature effect on quantum tunneling in a Cooper-pair-box coupled to a
quantum oscillator is studied by both numerical and analytical calculations. It
is found that, in strong coupling regions, coherent tunneling of a
Cooper-pair-box can be destroyed by its coupling to a quantum oscillator and
the tunneling becomes thermally activated as the temperature rises, leading to
failure of the Cooper-pair-box. The transition temperature between the coherent
tunneling and thermo-activated hopping is determined and physics analysis based
on small polaron theory is also provided.


title: On the Existence of Symplectic Resolutions of Symplectic Reductions

abstract:
  We compute the symplectic reductions for the action of Sp_2n on several
copies of C^2n and for all coregular representations of Sl_2. If it exists we
give at least one symplectic resolution for each example. In the case Sl_2
acting on sl_2+C^2 we obtain an explicit description of Fu's and Namikawa's
example of two non-equivalent symplectic resolutions connected by a Mukai flop.


title:
An elementary approach to Stochastic Differential Equations using the
  infinitesimals

abstract:
  The aim of this paper is to evidence two points relative to Nonstandard
analysis (NSA): 1. In most applications of NSA to analysis, only elementary
facts and techniques of nonstandard calculus seems to be necessary. 2. The
advantages of a theory which includes infinitesimals rely more on the
possibility of making new models rather than in the proving techniques.
  These two points will be illustrated in the theory of Brownian motion which
can be considered as a classical model to test the power of the infinitesimal
approach. Starting from a naive idea of Brownian motion, we deduce the
Fokker-Plank equation in a simple and rigorous way. It is possible to keep
every things to a simple level since all the theory of stochastic differential
equations is treated as a hyperfinite theory and it is not translated in a
"standard model". The only standard object is the final one: the Fokker-Plank
equation.


title:
Thermodynamics of the Maxwell-Gauss-Bonnet anti-de Sitter Black Hole
  with Higher Derivative Gauge Corrections

abstract:
  The local and global thermal phase structure for asymptotically anti-de
Sitter black holes charged under an abelian gauge group, with both Gauss-Bonnet
and quartic field strength corrections, is mapped out for all parameter space.
We work in the grand canonical ensemble where the external electric potential
is held fixed. The analysis is performed in an arbitrary number of dimensions,
for all three possible horizon topologies - spherical, flat or hyperbolic. For
spherical horizons, new metastable configurations are exhibited both for the
pure Gauss-Bonnet theory as well as the pure higher derivative gauge theory and
combinations thereof. In the pure Gauss-Bonnet theory with negative coefficient
and five or more spatial dimensions, two locally thermally stable black hole
solutions are found for a given temperature. Either one or both of them may be
thermally favored over the anti-de Sitter vacuum - corresponding to a single or
a double decay channel for the metastable black hole. Similar metastable
configurations are uncovered for the theory with pure quartic field strength
corrections, as well combinations of the two types of corrections, in three or
more spatial dimensions. Finally, a secondary Hawking-Page transition between
the smaller thermally favored black hole and thermal anti-de Sitter space is
observed when both corrections are turned on and their couplings are both
positive.


title:
Asymptotic analysis for a simple explicit estimator in Barndorff-Nielsen
  and Shephard stochastic volatility models

abstract:
  We provide a simple explicit estimator for discretely observed
Barndorff-Nielsen and Shephard models, prove rigorously consistency and
asymptotic normality based on the single assumption that all moments of the
stationary distribution of the variance process are finite, and give explicit
expressions for the asymptotic covariance matrix.
  We develop in detail the martingale estimating function approach for a
bivariate model, that is not a diffusion, but admits jumps. We do not use
ergodicity arguments.
  We assume that both, logarithmic returns and instantaneous variance are
observed on a discrete grid of fixed width, and the observation horizon tends
to infinity. As the instantaneous variance is not observable in practice, our
results cannot be applied immediately. Our purpose is to provide a theoretical
analysis as a starting point and benchmark for further developments concerning
optimal martingale estimating functions, and for theoretical and empirical
investigations, that replace the variance process with a substitute, such as
number or volume of trades or implied variance from option data.


title: On the Superconductivity of LaFe1-yCoyAsO1-xFx

abstract:
  We have prepared the superconducting system LaFe1-yCoyAsO1-xFx (x=0.11) and
carried out measurements of their electrical resistivities r and
superconducting diamagnetisms. 75As- and 135La-NMR studies have also been
carried out. The Knight shift observed for 75As has been found to be suppressed
by the superconductivity, while for 135La, the shift is almost insensitive to
the superconductivity. This result presents rather strong experimental evidence
for the singlet pairing. The Co-doping effect on the superconducting transition
temperature Tc is not so significant as expected for superconductors with
nodes, suggesting that the potential scattering does not seem to primarily
suppress the superconductivity. Even for superconductors without nodes, it may
not be so trivial to expect this small effect, if there are two different
(disconnected) Fermi surfaces whose order parameters have opposite signs. As a
possible explanation of this small Tc suppression seems to be related with the
loss of the itinerant nature of the electrons.


title:
Mass and Magnetic Moments of the Heavy Flavored Baryons with $J=3/2$ in
  Light Cone QCD Sum Rules

abstract:
  Inspired by the results of recent experimental discoveries for charm and
bottom baryons, the masses and magnetic moments of the heavy baryons with
$J^P=3/2^+$ containing a single heavy quark are studied within light cone QCD
sum rules method. Our results on the masses of heavy baryons are in good
agreement with predictions of other approaches, as well as with the existing
experimental values. Our predictions on the masses of the states, which are not
yet discovered in the experiments, can be tested in the future experiments. A
comparison of our results on the magnetic moments of these baryons and the
hyper central model predictions is presented.


title:
Search for solar hadronic axions produced by a bremsstrahlung-like
  process

abstract:
  We have searched for hadronic axions which may be produced in the Sun by a
bremsstrahlung-like process, and observed in the HPGe detector by an
axioelectric effect. A conservative upper limit on the hadronic axion mass m_a
< 334 eV at 95% C.L. is obtained. Our experimental approach is based on the
axion-electron coupling and it does not include the axion-nucleon coupling,
which suffers from the large uncertainties related to the estimation of the
flavor-singlet axial-vector matrix element.


title:
Implementing general belief function framework with a practical
  codification for low complexity

abstract:
  In this chapter, we propose a new practical codification of the elements of
the Venn diagram in order to easily manipulate the focal elements. In order to
reduce the complexity, the eventual constraints must be integrated in the
codification at the beginning. Hence, we only consider a reduced hyper power
set $D_r^\Theta$ that can be $2^\Theta$ or $D^\Theta$. We describe all the
steps of a general belief function framework. The step of decision is
particularly studied, indeed, when we can decide on intersections of the
singletons of the discernment space no actual decision functions are easily to
use. Hence, two approaches are proposed, an extension of previous one and an
approach based on the specificity of the elements on which to decide. The
principal goal of this chapter is to provide practical codes of a general
belief function framework for the researchers and users needing the belief
function theory.


title: Bose-Einstein condensation of stationary-light polaritons

abstract:
  We propose and analyze a mechanism for Bose-Einstein condensation of
stationary dark-state polaritons. Dark-state polaritons (DSPs) are formed in
the interaction of light with laser-driven 3-level Lambda-type atoms and are
the basis of phenomena such as electromagnetically induced transparency (EIT),
ultra-slow and stored light. They have long intrinsic lifetimes and in a
stationary set-up with two counterpropagating control fields of equal intensity
have a 3D quadratic dispersion profile with variable effective mass. Since DSPs
are bosons they can undergo a Bose-Einstein condensation at a critical
temperature which can be many orders of magnitude larger than that of atoms. We
show that thermalization of polaritons can occur via elastic collisions
mediated by a resonantly enhanced optical Kerr nonlinearity on a time scale
short compared to the decay time. Finally condensation can be observed by
turning stationary into propagating polaritons and monitoring the emitted
light.


title: Some Comments on Dynamical Character of Cosmological Constant and GUP

abstract:
  In this paper the results obtained by Minic and his colleagues on the
uncertainty relation of the pair "cosmological constant - volume of
space-time", where cosmological constant is a dynamical quantity, are
reconsidered and generalized proceeding from a more natural viewpoint. It is
demonstrated that on the basis of simple and natural assumptions this relation
may be understood with the help of the uncertainty relation for the pair
"energy - time". Since the latter is generalized at Planck's scales (Early
Universe)- GUP, the first one may be generalized in a similar way. This means
that we can suggest GUP for the pair "cosmological constant - space-time
volume". Here the relation is derived in the explicit form, and also some
implications are considered.


title: On Gribov's supercriticality picture of quark confinement

abstract:
  Some years ago Gribov developed the so-called supercritical light quark
confinement scenario. Based on physical arguments he conjectured a drastic
change in the analytical properties of the quark propagator when the
back-reaction of Goldstone bosons (pions) is considered. We investigate this
scenario and provide numerical solutions for the quark propagator in the
complex plane with and without the pion back-reaction. We find no evidence for
the scenario Gribov advocated. As an aside we present a novel method to solve
the quark Dyson-Schwinger equation in the complex plane and discuss new
characteristics of dynamical chiral symmetry breaking in our truncation scheme.


title: Mirrorless Negative-index Parametric Micro-oscillator

abstract:
  The feasibility and extraordinary properties of mirrorless parametric
oscillations in strongly absorbing negative-index metamaterials are shown. They
stem from the backwardness of electromagnetic waves inherent to this type of
metamaterials.


title:
Pion electromagnetic form factor, perturbative QCD, and large-Nc Regge
  models

abstract:
  We present a construction of the pion electromagnetic form factor where the
transition from large-Nc Regge vector meson dominance models with infinitely
many resonances to perturbative QCD is built in explicitly. The construction is
based on an appropriate assignment of residues to the Regge poles, which
fulfills the constraints of the parton-hadron duality and perturbative QCD. The
model contains a slowly falling off non-perturbative contribution which
dominates over the perturbative QCD radiative corrections for the
experimentally accessible momenta. The leading order and next-to-leading order
calculations show a converging pattern which describes the available data
within uncertainties, while the onset of asymptotic QCD takes place at
extremely high momenta, Q ~ 10^3-10^4 GeV. The method can be straightforwardly
extended to study other form factors where the perturbative QCD result is
available.


title: Frequency locking in the injection-locked frequency divider equation

abstract:
  We consider a model for the injection-locked frequency divider, and study
analytically the locking onto rational multiples of the driving frequency. We
provide explicit formulae for the width of the plateaux appearing in the
devil's staircase structure of the lockings, and in particular show that the
largest plateaux correspond to even integer values for the ratio of the
frequency of the driving signal to the frequency of the output signal. Our
results prove the experimental and numerical results available in the
literature.


title:
Preconditioned HSS Method for Finite Element Approximations of
  Convection-Diffusion Equations

abstract:
  A two-step preconditioned iterative method based on the
Hermitian/Skew-Hermitian splitting is applied to the solution of nonsymmetric
linear systems arising from the Finite Element approximation of
convection-diffusion equations. The theoretical spectral analysis focuses on
the case of matrix sequences related to FE approximations on uniform structured
meshes, by referring to spectral tools derived from Toeplitz theory. In such a
setting, if the problem is coercive, and the diffusive and convective
coefficients are regular enough, then the proposed preconditioned matrix
sequence shows a strong clustering at unity, i.e., a superlinear
preconditioning sequence is obtained. Under the same assumptions, the
optimality of the PHSS method is proved and some numerical experiments confirm
the theoretical results. Tests on unstructured meshes are also presented,
showing the some convergence behavior.


title:
Scaling dimension of fidelity susceptibility in quantum phase
  transitions

abstract:
  We analyze ground-state behaviors of fidelity susceptibility (FS) and show
that the FS has its own distinct dimension instead of real system's dimension
in general quantum phases. The scaling relation of the FS in quantum phase
transitions (QPTs) is then established on more general grounds. Depending on
whether the FS's dimensions of two neighboring quantum phases are the same or
not, we are able to classify QPTs into two distinct types. For the latter type,
the change in the FS's dimension is a characteristic that separates two phases.
As a non-trivial application to the Kitaev honeycomb model, we find that the FS
is proportional to $L^2\ln L$ in the gapless phase, while $L^2$ in the gapped
phase. Therefore, the extra dimension of $\ln L$ can be used as a
characteristic of the gapless phase.


title: The Garman-Klass volatility estimator revisited

abstract:
  The Garman-Klass unbiased estimator of the variance per unit time of a
zero-drift Brownian Motion B, based on the usual financial data that reports
for time windows of equal length the open (OPEN), minimum (MIN), maximum (MAX)
and close (CLOSE) values, is quadratic in the statistic S1=(CLOSE-OPEN,
OPEN-MIN, MAX-OPEN). This estimator, with efficiency 7.4 with respect to the
classical estimator (CLOSE-OPEN)^2, is widely believed to be of minimal
variance. The current report disproves this belief by exhibiting an unbiased
estimator with slightly but strictly higher efficiency 7.7322. The essence of
the improvement lies in the observation that the data should be compressed to
the statistic S2 defined on W(t)= B(0)+[B(t)-B(0)]sign[(B(1)-B(0)] as S1 was
defined on the Brownian path B(t). The best S2-based quadratic unbiased
estimator is presented explicitly. The Cramer-Rao upper bound for the
efficiency of unbiased estimators, corresponding to the efficiency of
large-sample Maximum Likelihood estimators, is 8.471. This bound cannot be
attained because the distribution is not of exponential type. Regression-fitted
quadratic functions of S2 (with mean 1) markedly out-perform those of S1 when
applied to random walks with heavy-tail-distributed increments. Performance is
empirically studied in terms of the tail parameter.


title: On the Cuts of Scattering Amplitudes

abstract:
  The use of complex analysis for computing one-loop scattering amplitudes is
naturally induced by generalised unitarity-cut conditions, fulfilled by complex
values of the loop variable. We report on two techniques: the cut-integration
with spinor-variables as contour integrals of rational functions; and the use
of the Discrete Fourier Transform to optimize the reduction of tensor-integrals
to master scalar integrals.


title:
Applications of the optical fiber to the generation and to the
  measurement of low-phase-noise microwave signals

abstract:
  The optical fiber used as a microwave delay line exhibits high stability and
low noise and makes accessible a long delay (>100 microseconds) in a wide
bandwidth (about 40 GHz, limited by the optronic components). Hence, it finds
applications as the frequency reference in microwave oscillators and as the
reference discriminator for the measurement of phase noise. The fiber is
suitable to measure the oscillator stability with a sensitivity of parts in
1E-12. Enhanced sensitivity is obtained with two independent delay lines, after
correlating and averaging. Short-term stability of parts in 1E-12 is achieved
inserting the delay line in an oscillator. The frequency can be set in steps
multiple of the inverse delay, which is in the 10-100 kHz region.
  This article adds to the available references a considerable amount of
engineering and practical knowledge, the understanding of 1/f noise,
calibration, the analysis of the cross-spectrum technique to reduce the
instrument background, the phase-noise model of the oscillator, and the
experimental test of the oscillator model.


title: Gap solitons in a model of a superfluid fermion gas in optical lattices

abstract:
  We consider a dynamical model for a Fermi gas in the
Bardeen-Cooper-Schrieffer (BCS) superfluid state, trapped in a combination of a
1D or 2D optical lattice (OL) and a tight parabolic potential acting in the
transverse direction(s). The model is based on an equation for the order
parameter (wave function), which is derived from the energy density for the
weakly coupled BCS superfluid. The equation includes a nonlinear self-repulsive
term of power 7/3, which accounts for the Fermi pressure. Reducing the equation
to the 1D or 2D form, we construct families of stable 1D and 2D gap solitons
(GSs) by means of numerical simulations, which are guided by the variational
approximation (VA). The GSs are, chiefly, compact objects trapped in a single
cell of the OL potential. In the linear limit, the VA predicts almost exact
positions of narrow Bloch bands that separate the semi-infinite and first
finite gaps, as well as the first and second finite ones. Families of stable
even and odd bound states of 1D GSs are constructed too. We also demonstrate
that the GS can be dragged without much distortion by an OL moving at a
moderate velocity ($\sim $ 1 mm/s, in physical units). The predicted GSs
contain $\sim 10^{3}-10^{4}$ and $\sim 10^{3}$ atoms per 1D and 2D settings,
respectively.


title: The mysterious Of?p class and the magnetic O-star Theta Ori C

abstract:
  In recent years, the stars of the Of?p category have revealed a wealth of
peculiar phenomena: varying line profiles, photometric changes, and X-ray
overluminosity are only a few of their characteristics. Here we review their
physical properties, to facilitate comparisons among the Galactic members of
this class. As one of them has been proposed to resemble the magnetic oblique
rotator Theta Ori C, though with a longer period, this latter object is also
included in our study to illuminate its similarities and differences with the
Of?p category.


title: Non-thermal processes in the cluster of galaxies Abell 3376

abstract:
  We model the high-energy emission that results from the interaction of
relativistic particles with photons and matter in the cluster of galaxies Abell
3376. The presence of relativistic particles is inferred from the recently
found radio relics in this cluster, being one of the most prominent examples of
double opposite, giant ringlike radio structures. Assuming that diffusive shock
acceleration takes place in the cluster regions where radio relics are
observed, we calculate the spectral energy distribution resulting from the most
relevant non-thermal processes, which are synchrotron radiation, inverse
Compton scattering, relativistic Bremsstrahlung, and inelastic proton-proton
collisions. In the context of our model, the major radiative component at high
energies is inverse Compton scattering, which could reach luminosities L ~
9x10^{41} erg/s in the energy range between ~ 1 MeV and 10 TeV. Hadronic
interactions would yield a minor contribution to the overall non-thermal
emission, but would dominate at ultra-high energies. The cluster Abell 3376
might be detectable at gamma-rays by HESS, GLAST satellite and future planned
Cherenkov arrays.


title: Billiards in Nearly Isosceles Triangles

abstract:
  We prove that any sufficiently small perturbation of an isosceles triangle
has a periodic billiard path. Our proof involves the analysis of certain
infinite families of Fourier series that arise in connection with triangular
billiards, and reveals some self-similarity phenomena in irrational triangular
billiards. Our analysis illustrates the surprising fact that billiards on a
triangle near a Veech triangle is extremely complicated even though Billiards
on a Veech triangle is very well understood.


title: Modules with cosupport and injective functors

abstract:
  Several authors have studied the filtered colimit closure lim(B) of a class B
of finitely presented modules. Lenzing called lim(B) the category of modules
with support in B, and proved that it is equivalent to the category of flat
objects in the functor category (B^{op},Ab). In this paper, we study the
category (Mod-R)^B of modules with cosupport in B. We show that (Mod-R)^B is
equivalent to the category of injective objects in (B,Ab), and thus recover a
classical result by Jensen-Lenzing on pure injective modules. Works of
Angeleri-Hugel, Enochs, Krause, Rada, and Saorin make it easy to discuss
covering and enveloping properties of (Mod-R)^B, and furthermore we compare the
naturally associated notions of B-coherence and B-noetherianness. Finally, we
prove a number of stability results for lim(B) and (Mod-R)^B. Our applications
include a generalization of a result by Gruson-Jensen and Enochs on pure
injective envelopes of flat modules.


title:
Spatial correlation functions for the collective degrees of freedom of
  many trapped ions

abstract:
  Spatial correlation functions provide a glimpse into the quantum correlations
within a quantum system. Ions in a linear trap collectively form a nonuniform,
discretized background on which a scalar field of phonons propagates. Trapped
ions have the experimental advantage of each having their own "built-in"
motional detector: electronic states that can be coupled, via an external
laser, to the ion's vibrational motion. The post-interaction electronic state
can be read out with high efficiency, giving a stochastic measurement record
whose classical correlations reflect the quantum correlations of the ions'
collective vibrational state. Here we calculate this general result, then we
discuss the long detection-time limit and specialize to Gaussian states, and
finally we compare the results for thermal versus squeezed states.


title: On the rational monodromy-free potentials with sextic growth

abstract:
  We study the rational potentials $V(x)$, with sextic growth at infinity, such
that the corresponding one-dimensional \Sch equation has no monodromy in the
complex domain for all values of the spectral parameter. We investigate in
detail the subclass of such potentials which can be constructed by the Darboux
transformations from the well-known class of quasi-exactly solvable potentials
$$V= x^6 - \nu x^2 +\frac{l(l+1)}{x^2}.$$ We show that, in contrast with the
case of quadratic growth, there are monodromy-free potentials which have
quasi-rational eigenfunctions, but which can not be given by this construction.
We discuss the relations between the corresponding algebraic varieties, and
present some elementary solutions of the Calogero-Moser problem in the external
field with sextic potential.


title:
Modular Galois covers associated to symplectic resolutions of
  singularities

abstract:
  Let Y be a normal projective variety and p a morphism from X to Y, which is a
projective holomorphic symplectic resolution. Namikawa proved that the
Kuranishi deformation spaces Def(X) and Def(Y) are both smooth, of the same
dimension, and p induces a finite branched cover f from Def(X) to Def(Y). We
prove that f is Galois. We proceed to calculate the Galois group G, when X is
simply connected, and its holomorphic symplectic structure is unique, up to a
scalar factor. The singularity of Y is generically of ADE-type, along every
codimension 2 irreducible component B of the singular locus, by Namikawa's
work. The modular Galois group G is the product of Weyl groups of finite type,
indexed by such irreducible components B. Each Weyl group factor W_B is that of
a Dynkin diagram, obtained as a quotient of the Dynkin diagram of the
singularity-type of B, by a group of Dynkin diagram automorphisms.
  Finally we consider generalizations of the above set-up, where Y is affine
symplectic, or a Calabi-Yau threefold with a curve of ADE-singularities. We
prove that the morphism f from Def(X) to Def(Y) is a Galois cover of its image.
This explains the analogy between the above results and related work of
Nakajima, on quiver varieties, and of Szendroi on enhanced gauge symmetries for
Calabi-Yau threefolds.


title: stu Black Holes Unveiled

abstract:
  The general solutions of the radial attractor flow equations for extremal
black holes, both for non-BPS with non-vanishing central charge Z and for Z=0,
are obtained for the so-called stu model, the minimal rank-3 N=2 symmetric
supergravity in d=4 space-time dimensions. Comparisons with previous results,
as well as the fake supergravity (first order) formalism and an analysis of the
BPS bound all along the non-BPS attractor flows and of the marginal stability
of corresponding D-brane configurations, are given.