title: Improved mixing time bounds for the Thorp shuffle and L-reversal chain

abstract:
  We prove a theorem that reduces bounding the mixing time of a card shuffle to
verifying a condition that involves only pairs of cards, then we use it to
obtain improved bounds for two previously studied models.
  E. Thorp introduced the following card shuffling model in 1973. Suppose the
number of cards n is even. Cut the deck into two equal piles. Drop the first
card from the left pile or from the right pile according to the outcome of a
fair coin flip. Then drop from the other pile. Continue this way until both
piles are empty. We obtain a mixing time bound of O(log^4 n). Previously, the
best known bound was O(log^{29} n) and previous proofs were only valid for n a
power of 2.
  We also analyze the following model, called the L-reversal chain, introduced
by Durrett. There are n cards arrayed in a circle. Each step, an interval of
cards of length at most L is chosen uniformly at random and its order is
reversed. Durrett has conjectured that the mixing time is O(max(n, n^3/L^3) log
n). We obtain a bound that is within a factor O(log^2 n) of this,the first
bound within a poly log factor of the conjecture.


title:
Drift instabilities in the solar corona within the multi-fluid
  description

abstract:
  Recent observations revealed that the solar atmosphere is highly structured
in density, temperature and magnetic field. The presence of these gradients may
lead to the appearance of currents in the plasma, which in the weakly
collisional corona can constitute sources of free energy for driving
micro-instabilities. Such instabilities are very important since they represent
a possible source of ion-cyclotron waves which have been conjectured to play a
prominent role in coronal heating, but whose solar origin remains unclear.
Considering a density stratification transverse to the magnetic field, this
paper aims at studying the possible occurrence of gradient-induced plasma
micro-instabilities under typical conditions of coronal holes. Taking into
account the WKB (Wentzel-Kramers-Brillouin) approximation, we perform a Fourier
plane waves analysis using the collisionless multi-fluid model. By neglecting
the electron inertia, this model allows us to take into account ion-cyclotron
wave effects that are absent from the one-fluid model of magnetohydrodynamics
(MHD). Realistic models of density and temperature, as well as a 2-D analytical
magnetic-field model, are used to define the background plasma in the
open-field funnel in a polar coronal hole. The ray-tracing theory is used to
compute the ray path of the unstable waves, as well as the evolution of their
growth rates during the propagation. We demonstrate that in typical coronal
hole conditions, and when assuming typical transverse density length scales
taken from radio observations, the current generated by a relative electron-ion
drift provides enough free energy for driving the mode unstable. This
instability results from a coupling between oppositely propagating slow-mode
waves.


title:
Determination of the Fermion Pair Size in a Resonantly Interacting
  Superfluid

abstract:
  Fermionic superfluidity requires the formation of pairs. The actual size of
these fermion pairs varies by orders of magnitude from the femtometer scale in
neutron stars and nuclei to the micrometer range in conventional
superconductors. Many properties of the superfluid depend on the pair size
relative to the interparticle spacing. This is expressed in BCS-BEC crossover
theories, describing the crossover from a Bardeen-Cooper-Schrieffer (BCS) type
superfluid of loosely bound and large Cooper pairs to Bose-Einstein
condensation (BEC) of tightly bound molecules. Such a crossover superfluid has
been realized in ultracold atomic gases where high temperature superfluidity
has been observed. The microscopic properties of the fermion pairs can be
probed with radio-frequency (rf) spectroscopy. Previous work was difficult to
interpret due to strong and not well understood final state interactions. Here
we realize a new superfluid spin mixture where such interactions have
negligible influence and present fermion-pair dissociation spectra that reveal
the underlying pairing correlations. This allows us to determine the
spectroscopic pair size in the resonantly interacting gas to be 2.6(2)/kF (kF
is the Fermi wave number). The pairs are therefore smaller than the
interparticle spacing and the smallest pairs observed in fermionic superfluids.
This finding highlights the importance of small fermion pairs for superfluidity
at high critical temperatures. We have also identified transitions from fermion
pairs into bound molecular states and into many-body bound states in the case
of strong final state interactions.


title: The Case for Structured Random Codes in Network Capacity Theorems

abstract:
  Random coding arguments are the backbone of most channel capacity
achievability proofs. In this paper, we show that in their standard form, such
arguments are insufficient for proving some network capacity theorems:
structured coding arguments, such as random linear or lattice codes, attain
higher rates. Historically, structured codes have been studied as a stepping
stone to practical constructions. However, K\"{o}rner and Marton demonstrated
their usefulness for capacity theorems through the derivation of the optimal
rate region of a distributed functional source coding problem. Here, we use
multicasting over finite field and Gaussian multiple-access networks as
canonical examples to demonstrate that even if we want to send bits over a
network, structured codes succeed where simple random codes fail. Beyond
network coding, we also consider distributed computation over noisy channels
and a special relay-type problem.


title: Geometric Scaling in Mueller-Navelet Jets

abstract:
  We argue that the production of Mueller-Navelet jets at the LHC represents a
convenient environment to study gluon saturation and high energy scattering in
the presence of unitarity corrections. We show that, in a suitable range of
transverse momenta for the produced jets, the cross section for the partonic
subprocess should exhibit geometric scaling. We point out that, in the presence
of a running coupling, the cross section for producing hard jets cannot be
fully computed in perturbation theory, not even after taking into account the
saturation effects: the non-perturbative physics affects the overall
normalization of the cross section, but not also its geometric scaling
behavior.


title: Approximate innerness and central triviality of endomorphisms

abstract:
  We introduce the notions of approximate innerness and central triviality for
endomorphisms on separable von Neumann factors, and we characterize them for
hyperfinite factors by Connes-Takesaki modules of endomorphisms and modular
endomorphisms which are introduced by Izumi. Our result is a generalization of
the corresponding result obtained by Kawahigashi-Sutherland-Takesaki in
automorphism case.


title:
Nonlinear diffraction of light beams propagating in photorefractive
  media with embedded reflecting wire

abstract:
  The theory of nonlinear diffraction of intensive light beams propagating
through photorefractive media is developed. Diffraction occurs on a reflecting
wire embedded in the nonlinear medium at relatively small angle with respect to
the direction of the beam propagation. It is shown that this process is
analogous to the generation of waves by a flow of a superfluid past an
obstacle. The ``equation of state'' of such a superfluid is determined by the
nonlinear properties of the medium. On the basis of this hydrodynamic analogy,
the notion of the ``Mach number'' is introduced where the transverse component
of the wave vector plays the role of the fluid velocity. It is found that the
Mach cone separates two regions of the diffraction pattern: inside the Mach
cone oblique dark solitons are generated and outside the Mach cone the region
of ``ship waves'' is situated. Analytical theory of ``ship waves'' is developed
and two-dimensional dark soliton solutions of the equation describing the beam
propagation are found. Stability of dark solitons with respect to their decay
into vortices is studied and it is shown that they are stable for large enough
values of the Mach number.


title:
Absolute calibration of Analog Detectors using Stimulated Parametric
  Down Conversion

abstract:
  Spontaneous parametric down conversion has been largely exploited as a tool
for absolute calibration of photon counting detectors, photomultiplier tubes or
avalanche photodiodes working in Geiger regime. In this work we investigate the
extension of this technique from very low photon flux of photon counting regime
to the absolute calibration of analog photodetectors at higher photon flux.
Moving toward higher photon rate, i.e. at high gain regime, with the
spontaneous parametric down conversion shows intrinsic limitations of the
method, while the stimulated parametric down conversion process, where a seed
beam properly injected into the crystal in order to increase the photon
generation rate in the conjugate arm, allows us to work around this problem. A
preliminary uncertainty budget is discussed.


title: Self-organized transient facilitated atomic transport in Pt/Al(111)

abstract:
  During the course of atomic transport in a host material, impurity atoms need
to surmount an energy barrier driven by thermodynamic bias or at ultra-low
temperatures by quantum tunneling. In the present article we demonstrate using
atomistic simulations that at ultra-low temperature transient inter-layer
atomic transport is also possible without tunneling when the Pt/Al(111)
impurity/host system self-organizes itself spontaneously into an intermixed
configuration. No such extremely fast athermal concerted process has been
reported before at ultra low temperatures. The outlined novel transient atomic
exchange mechanism could be of general validity. We find that the source of
ultra-low temperature heavy particle barrier crossing is intrinsic and no
external bias is necessary for atomic intermixing and surface alloying in Pt/Al
although the dynamic barrier height is few eV. The mechanism is driven by the
local thermalization of the Al(111) surface in a self-organized manner arranged
spontaneously by the system without any external stimulus. The core of the
short lived thermalized region reaches the local temperature of $\sim 1000$ K
(including few tens of Al atoms) while the average temperature of the
simulation cell is $\sim 3$ K. The transient facilitated intermixing process
also takes place with repulsive impurity-host interaction potential leading to
negative atomic mobility hence the atomic injection is largely independent of
the strength of the impurity-surface interaction. We predict that similar
exotic behaviour is possible in other materials as well.


title:
Thermospin Hall effect generated by thermal influence and thermoelectric
  effect

abstract:
  In this paper, we present the theoretical predication of a thermospin Hall
effect, in which a transverse spin current can be generated in semiconductors
in the presence of spin-orbit coupling by a frequency-dependent longitudinal
temperature gradient. Because of the thermoelectric effect, there is no net
charge current but there is a heat flow from the hot side to the cold side. We
perform the theoretical calculation of dynamical thermospin Hall conductivity
in a two-dimensional Rashba spintronic system. It has been shown that the
direct interband optical transition dominates the ordering and manipulation of
spin in the generation of a transverse intrinsic spin current. In view of the
role of the thermoelectric effect, the contributions to the thermospin Hall
effect are classified as that originating from a direct contribution of thermal
electronic diffusion and that from the compensatory electron flow in balance
with the thermal diffusion. For a finite system, the analysis yields evidence
that the spin accumulation around the edges of a plate determines the
magnetization. In equilibrium, a field created by a magnetization gradient
emerges in the direction perpendicular to the temperature gradient. The
experimental observation of the thermospin Hall effect is proposed by measuring
the longitudinal temperature difference with the injection of a transverse spin
current and by analyzing the Hall angle. In addition, in order to achieve pure
spin accumulation in the spin Hall effect, an extension of the thermospin Hall
effect for exciting electron-hole pairs in semiconductors is proposed.


title:
Exact exponential bounds for the random field maximum distribution via
  the majoring measures (generic chaining)

abstract:
  In this paper non-asymptotic exact exponential estimates are derived for the
tail of maximum distribution of random field in the terms of majoring measures
or, equally, generic chaining.


title: PSR J0737-3039: Interacting Pulsars in X-Rays

abstract:
  We present the results of a ~230 ks long X-ray observation of the
relativistic double-pulsar system PSR J0737-3039 obtained with the XMM-Newton
satellite in 2006 October. We confirm the detection in X-rays of pulsed
emission from PSR J0737-3039A (PSR A), mostly ascribed to a soft non-thermal
power-law component (photon index ~ 3.3) with a 0.2-3 keV luminosity of
~1.9E+30 erg/s (assuming a distance of 500 pc). For the first time, pulsed
X-ray emission from PSR J0737-3039B (PSR B) is also detected in part of the
orbit. This emission, consistent with thermal radiation with temperature kT=30
eV and a bolometric luminosity of ~1E+32 erg/s, is likely powered by heating of
PSR B's surface caused by PSR A's wind. A hotter (~130 eV) and fainter (~5E+29
erg/s) thermal component, probably originating from back-falling particles
heating polar caps of either PSR A or PSR B is also required by the data. No
signs of X-ray emission from a bow-shock between PSR A's wind and the
interstellar medium or PSR B's magnetosphere are present. The upper limit on
the luminosity of such a shock component (~1E+29 erg/s) constrains the wind
magnetization parameter sigma of PSR A to values greater than 1.


title: Path Loss Exponent Estimation in a Large Field of Interferers

abstract:
  In wireless channels, the path loss exponent (PLE) has a strong impact on the
quality of links, and hence, it needs to be accurately estimated for the
efficient design and operation of wireless networks. In this paper, we address
the problem of PLE estimation in large wireless networks, which is relevant to
several important issues in networked communications such as localization,
energy-efficient routing, and channel access. We consider a large ad hoc
network where nodes are distributed as a homogeneous Poisson point process on
the plane and the channels are subject to Nakagami-m fading. We propose and
discuss three distributed algorithms for estimating the PLE under these
settings which explicitly take into account the interference in the network. In
addition, we provide simulation results to demonstrate the performance of the
algorithms and quantify the estimation errors. We also describe how to estimate
the PLE accurately even in networks with spatially varying PLEs and more
general node distributions.


title:
Spin Dynamics of $Ni Cl_2-4SC(NH_2)_2$ in the Field-Induced Ordered
  Phase

abstract:
  $Ni Cl_2$-$4SC(NH_2)_2$ (known as DTN) is a spin-1 material with a strong
single-ion anisotropy that is regarded as a new candidate for Bose-Einstein
condensation (BEC) of spin degrees of freedom. We present a systematic study of
the low-energy excitation spectrum of DTN in the field-induced magnetically
ordered phase by means of high-field electron spin resonance measurements at
temperatures down to 0.45 K. We argue that two gapped modes observed in the
experiment can be consistently interpreted within a four-sublattice
antiferromagnet model with a finite interaction between two tetragonal
subsystems and unbroken axial symmetry. The latter is crucial for the
interpretation of the field-induced ordering in DTN in terms of BEC.


title:
Spectroscopy of superconducting charge qubits coupled by a Josephson
  inductance

abstract:
  We have designed and experimentally implemented a circuit of
inductively-coupled superconducting charge qubits, where a Josephson junction
is used as an inductance, and the coupling between the qubits is controlled by
an applied magnetic flux. Spectroscopic measurements on the circuit are in good
agreement with theoretical calculations. We observed anticrossings which
originate from the coupling between the qubit and the plasma mode of the
Josephson junction. Moreover, the size of the anticrossing depends on the
external magnetic flux, which demonstrates the controllability of the coupling.


title: Path integration and perturbation theory with complex Euclidean actions

abstract:
  The Euclidean path integral quite often involves an action that is not
completely real {\it i.e.} a complex action. This occurs when the Minkowski
action contains $t$-odd CP-violating terms. Analytic continuation to Euclidean
time yields an imaginary term in the Euclidean action. In the presence of
imaginary terms in the Euclidean action, the usual method of perturbative
quantization can fail. Here the action is expanded about its critical points,
the quadratic part serving to define the Gaussian free theory and the higher
order terms defining the perturbative interactions. For a complex action, the
critical points are generically obtained at complex field configurations. Hence
the contour of path integration does not pass through the critical points and
the perturbative paradigm cannot be directly implemented. The contour of path
integration has to be deformed to pass through the complex critical point using
a generalized method of steepest descent, in order to do so. Typically, what is
done is that only the real part of the Euclidean action is considered, and its
critical points are used to define the perturbation theory. In this article we
present a simple 0+1-dimensional example, of $N$ scalar fields interacting with
a U(1) gauge field, in the presence of a Chern-Simons term, where
alternatively, the path integral can be done exactly, the procedure of
deformation of the contour of path integration can be done explicitly and the
standard method of only taking into account the real part of the action can be
followed. We show explicitly that the standard method does not give a correct
perturbative expansion.


title: Trans-Planckian Physics and Non-Commutative Inflation

abstract:
  Non-commutativity of spacetime at the Planck scale may deform the usual
dispersion relations. And these deformed dispersion relations could lead to the
accelerating phase without a scalar field. In this paper, we have calculated
the spectral index and the running of spectral index in a non-commutative
inflation model. Non-commutative inflation with thermal radiation gives a scale
invariant spectrum in the limit $w \to -1$ and negative running spectral index
which are consistent with the WMAP 3-year results.


title:
Effects of kink and flexible hinge defects on mechanical responses of
  short double stranded DNA molecules

abstract:
  We predict various detectable mechanical responses to the presence of local
DNA defects which are defined as short DNA segments exhibiting mechanical
properties obviously different from the 50 nm persistence length based
semiflexible polymer model. The defects discussed are kinks and flexible hinges
either permanently fixed on DNA or thermally excited. Their effects on
extension shift, the effective persistence length, the end-to-end distance
distribution, and the cyclization probability are computed using a
transfer-matrix method. Our predictions will be useful in future experimental
designs to study DNA nicks or mismatch base pairs, mechanics of specific DNA
sequences, and specific DNA-protein interaction using magnetic tweezer,
fluorescence resonance energy transfer or plasmon resonance technique, and the
traditional biochemistry cyclization probability measurements.


title: Polynomial Poisson structures on affine solvmanifolds

abstract:
  A $n$-dimensional Lie group $G$ equipped with a left invariant symplectic
form $\om^+$ is called a symplectic Lie group. It is well-known that $\om^+$
induces a left invariant affine structure on $G$. Relatively to this affine
structure we show that the left invariant Poisson tensor $\pi^+$ corresponding
to $\om^+$ is polynomial of degree 1 and any right invariant $k$-multivector
field on $G$ is polynomial of degree at most $k$. If $G$ is unimodular, the
symplectic form $\om^+$ is also polynomial and the volume form
$\wedge^{\frac{n}2}\om^+$ is parallel. We show also that any left invariant
tensor field on a nilpotent symplectic Lie group is polynomial, in particular,
any left invariant Poisson structure on a nilpotent symplectic Lie group is
polynomial. Because many symplectic Lie groups admit uniform lattices, we get a
large class of polynomial Poisson structures on compact affine solvmanifolds.


title: Classical Correlation in Quantum Dialogue

abstract:
  Classical communications are used in the post-processing procedure of quantum
key distribution. Since the security of quantum key distribution is based on
the principles of quantum mechanics, intuitively the secret key can only be
derived from the quantum states. We find that classical communications are
incorrectly used in the so-called quantum dialogue type protocols. In these
protocols, public communications are used to transmit secret messages. Our
calculations show that half of Alice's and Bob's secret message is leaked
through classical channel. By applying Holevo bound, we can see that the
quantum efficiency claimed in the quantum dialogue type of protocols is not
achievable.


title:
Hamiltonian stationary cones and self-similar solutions in higher
  dimension

abstract:
  In [LW], we construct examples of two-dimensional Hamiltonian stationary
self-shrinkers and self-expanders for Lagrangian mean curvature flows, which
are asymptotic to the union of two Schoen-Wolfson cones. These self-shrinkers
and self-expanders can be glued together to yield solutions of the Brakke flow
- a weak formulation of the mean curvature flow. Moreover, there is no mass
loss along the Brakke flow. In this paper, we generalize these results to
higher dimension. We construct new higher dimensional Hamiltonian stationary
cones of different topology as generalizations of the Schoen-Wolfson cones.
Hamiltonian stationary self-shrinkers and self-expanders that are asymptotic to
these Hamiltonian stationary cones are also constructed. They can also be glued
together to produce eternal solutions of the Brakke flow without mass loss.
Finally, we show the same conclusion holds for those Lagrangian self-similar
examples recently found by Joyce, Tsui and the first author in [JLT].


title:
Supernova remnants, planetary nebulae and superbubbles: prospects for
  new XMM-Newton observations

abstract:
  Important results achieved over the last years on supernova remnants,
planetary nebulae and superbubbles are briefly reviewed in the context of X-ray
observations. I intend to review the important open scientific questions in
these fields, and the specific contributions that can be made by XMM-Newton.


title: Automorphic forms of higher order

abstract:
  In this paper a theory of Hecke operators for higher order modular forms is
established. The definition of cusp forms and attached L-functions is extended
beyond the realm of parabolic invariants. The role of representation theoretic
methods is clarified and, motivated by higher order forms, new convolution
products of L-functions are introduced.


title: Three-dimensional character of atom-chip-based rf-dressed potentials

abstract:
  We experimentally investigate the properties of radio-frequency-dressed
potentials for Bose-Einstein condensates on atom chips. The three-dimensional
potential forms a connected pair of parallel waveguides. We show that
rf-dressed potentials are robust against the effect of small magnetic-field
variations on the trap potential. Long-lived dipole oscillations of condensates
induced in the rf-dressed potentials can be tuned to a remarkably low damping
rate. We study a beam-splitter for Bose-Einstein condensates and show that a
propagating condensate can be dynamically split in two vertically separated
parts and guided along two paths. The effect of gravity on the potential can be
tuned and compensated for using a rf-field gradient.


title: Kaons and antikaons in asymmetric nuclear matter

abstract:
  The properties of kaons and antikaons and their modification in isospin
asymmetric nuclear matter are investigated using a chiral SU(3) model. These
isospin dependent medium effects are important for asymmetric heavy ion
collision experiments. In the present work, the medium modifications of the
energies of the kaons and antikaons, within the asymmetric nuclear matter,
arise due to the interactions of kaons and antikaons with the nucleons and
scalar mesons. The values of the parameters in the model are obtained by
fitting the saturation properties of nuclear matter and kaon-nucleon scattering
lengths. The pion-nucleon scattering lengths are also calculated within the
chiral effective model and compared with earlier results from the literature.
The density dependence of the isospin asymmetry is seen to be appreciable for
the kaon and antikaon optical potentials. This can be particularly relevant for
the future accelerator facility FAIR at GSI, where experiments using neutron
rich beams are planned to be used in the study of compressed baryonic matter.


title:
Linear plasmon dispersion in single-wall carbon nanotubes and the
  collective excitation spectrum of graphene

abstract:
  We have measured a strictly linear pi-plasmon dispersion along the axis of
individualized single wall carbon nanotubes, which is completely different from
plasmon dispersions of graphite or bundled single wall carbon nanotubes.
Comparative ab initio studies on graphene based systems allow us to reproduce
the different dispersions. This suggests that individualized nanotubes provide
viable experimental access to collective electronic excitations of graphene,
and it validates the use of graphene to understand electronic excitations of
carbon nanotubes. In particular, the calculations reveal that local field
effects (LFE) cause a mixing of electronic transitions, including the 'Dirac
cone', resulting in the observed linear dispersion.


title: Non-ideal atom-light interfaces: modeling real-world effects

abstract:
  We present a model which describes coherent and incoherent processes in
continuous-variable atom-light interfaces. We assume Gaussian states for light
and atoms and formulate the system dynamics in terms of first and second
moments of the angular momentum operators. Spatial and temporal inhomogeneities
in light and atom variables are incorporated by partitioning the system into
small homogeneous segments. Furthermore, other experimental imperfections as
for instance limited detector time-resolution and atomic motion are simulated.
The model is capable of describing many experimental situations ranging from
room temperature vapor cells to sub-mK atomic clouds. To illustrate the method,
we calculate the effect of detector time-resolution, spatial inhomogeneities
and atomic motion on the spin squeezing dynamics of rubidium 87 on the D2
transition.


title:
Current-induced spin polarization in spin-orbit-coupled two-dimensional
  electron systems

abstract:
  Current-induced spin polarization (CISP) is rederived in ballistic
spin-orbit-coupled electron systems, based on equilibrium statistical
mechanics. A simple and useful picture is correspondingly proposed to help
understand the CISP and predict the polarization direction. Nonequilibrium
Landauer-Keldysh formalism is applied to demonstrate the validity of the
statistical picture, taking the linear Rashba-Dresselhaus [001] two-dimensional
system as a specific example. Spin densities induced by the CISP in
semiconductor heterostructures and in metallic surface states are compared,
showing that the CISP increases with the spin splitting strength and hence
suggesting that the CISP should be more observable on metal and semimetal
surfaces due to the discovered strong Rashba splitting. An application of the
CISP designed to generate a spin-Hall pattern in the inplane, instead of the
out-of-plane, component is also proposed.


title: Symmetry classification of third-order nonlinear evolution equations

abstract:
  We give a Lie-algebraic classification of third order quasilinear equations
which admit non-trivial Lie point symmetries.


title:
Dynamical symmetry breaking of lambda and vee-type three-level systems
  on quantization of the field modes

abstract:
  We develop a scheme to construct the Hamiltonians of the lambda, vee and
cascade type of three-level configurations using the generators of SU(3) group.
It turns out that this approach provides a well defined selection rule to give
different Hamitonians for each configurations. The lambda and vee type
configurations are exactly solved with different initial conditions while
taking the two-mode classical and quantized fields . For the classical field,
it is shown that the Rabi oscillation of the lambda model is similar to that of
the vee model and the dynamics of the vee model can be recovered from lambda
model and vice versa simply by inversion. We then proceed to solve the
quantized version of both models introducing a novel Euler matrix formalism. It
is shown that this dynamical symmetry exhibited in the Rabi oscillation of two
configurations for the semiclassical models is completely destroyed on
quantization of the field modes. The symmetry can be restored within the
quantized models when the field modes are both in the coherent states with
large average photon number which is depicted through the collapse and revival
of the Rabi oscillations.


title: Symplectic Automorphisms on Kummer Surfaces

abstract:
  Nikulin proved that the isometries induced on the second cohomology group of
a K3 surface $X$ by a finite abelian group $G$ of symplectic automorphisms are
essentially unique. Moreover he computed the discriminant of the sublattice of
$H^2(X, \Z)$ which is fixed by the isometries induced by $G$. However for
certain groups these discriminants are not the same of those found for explicit
examples. Here we describe Kummer surfaces for which this phenomena happens and
we explain the difference.


title:
Integral field spectroscopy of four lensed quasars: analysis of their
  neighborhood and evidence for microlensing

abstract:
  CONTEXT: Gravitationally lensed quasars constitute an independent tool to
derive H0 through time-delays; they offer as well the opportunity to study the
mass distribution and interstellar medium of their lensing galaxies and,
through microlensing they also allow one to study details of the emitting
source. AIMS: For such studies, one needs to have an excellent knowledge of the
close environment of the lensed images in order to model the lensing potential:
this means observational data over a large field-of-view and spectroscopy at
high spatial resolution. METHODS: We present VIMOS integral field observations
around four lensed quasars: HE 0230-2130, RX J0911.4+0551, H 1413+117 and B
1359+154. Using the low, medium and high resolution modes, we study the quasar
images and the quasar environments, as well as provide a detailed report of the
data reduction. RESULTS: Comparison between the quasar spectra of the different
images reveals differences for HE 0230-2130, RX J0911.4+0551 and H 1413+117:
flux ratios between the images of the same quasar are different when measured
in the emission lines and in the continuum. We have also measured the redshifts
of galaxies in the neighborhood of HE 0230-2130 and RX J0911.4+0551 which
possibly contribute to the total lensing potential. CONCLUSIONS: A careful
analysis reveals that microlensing is the most natural explanation for the
(de)magnification of the continuum emitting region of the background sources.
In HE 0230-2130, image D is likely to be affected by microlensing
magnification; in RX J0911.4+0551, images A1 and A3 are likely to be modified
by microlensing de-magnification and in H 1413+117, at least image D is
affected by microlensing.


title:
On steady-state currents through nano-devices: a scattering-states
  numerical renormalization group approach to open quantum systems

abstract:
  We propose a numerical renormalization group (NRG) approach to steady-state
currents through nano-devices. A discretization of the scattering-states
continuum ensures the correct boundary condition for an open quantum system. We
introduce two degenerate Wilson chains for current carrying left and
right-moving electrons reflecting time-reversal symmetry in the absence of a
finite bias $V$. We employ the time-dependent NRG to evolve the known
steady-state density operator for a non-interacting junction into the density
operator of the fully interacting nano-device at finite bias. We calculate the
temperature dependent current as function of $V$ and applied external magnetic
field using a recently developed algorithm for non-equilibrium spectral
functions.


title: Non-thermal acceleration mechanisms in supernova remnant shells

abstract:
  A review of the main issues in the field of particle acceleration in
Supernova Remnants is provided in the context of future X-ray observations with
Simbol-X. After a summary of the nonthermal acceleration mechanisms at work, I
briefly review the observations of supernova remnants in hard X-rays and in
gamma rays. Open issues are discussed in this framework.


title: Jensen's Inequality for g-Convex Function under g-Expectation

abstract:
  A real valued function defined on}$\mathbb{R}$ {\small is called}$g${\small
--convex if it satisfies the following \textquotedblleft generalized Jensen's
inequality\textquotedblright under a given}$g${\small -expectation, i.e.,
}$h(\mathbb{E}^{g}[X])\leq \mathbb{E}% ^{g}[h(X)]${\small, for all random
variables}$X$ {\small such that both sides of the inequality are meaningful. In
this paper we will give a necessary and sufficient conditions for a
}$C^{2}${\small -function being}$% g ${\small -convex. We also studied some
more general situations. We also studied}$g${\small -concave and}$g${\small
-affine functions.


title:
Far-field interaction of focused relativistic electron beams in electron
  energy loss spectroscopy of nanoscopic platelets

abstract:
  A quantum mechanical scattering theory for relativistic, highly focused
electron beams near nanoscopic platelets is presented, revealing a new
excitation mechanism due to the electron wave scattering from the platelet
edges. Radiative electromagnetic excitations within the light cone are shown to
arise, allowed by the breakdown of momentum conservation along the beam axis in
the inelastic scattering process. Calculated for metallic (silver and gold) and
insulating (SiO2 and MgO) nanoplatelets, new radiative features are revealed
above the main surface plasmon-polariton peak, and dramatic enhancements in the
electron energy loss probability at gaps of the 'classical' spectra, are found.
The corresponding radiation should be detectable in the vacuum far-field zone,
with e-beams exploited as sensitive 'tip-detectors' of electronically excited
nanostructures.


title:
Bias spectroscopy and simultaneous SET charge state detection of Si:P
  double dots

abstract:
  We report a detailed study of low-temperature (mK) transport properties of a
silicon double-dot system fabricated by phosphorous ion implantation. The
device under study consists of two phosphorous nanoscale islands doped to above
the metal-insulator transition, separated from each other and the source and
drain reservoirs by nominally undoped (intrinsic) silicon tunnel barriers.
Metallic control gates, together with an Al-AlOx single-electron transistor,
were positioned on the substrate surface, capacitively coupled to the buried
dots. The individual double-dot charge states were probed using source-drain
bias spectroscopy combined with non-invasive SET charge sensing. The system was
measured in linear (VSD = 0) and non-linear (VSD <> 0) regimes allowing
calculations of the relevant capacitances. Simultaneous detection using both
SET sensing and source-drain current measurements was demonstrated, providing a
valuable combination for the analysis of the system. Evolution of the triple
points with applied bias was observed using both charge and current sensing.
Coulomb diamonds, showing the interplay between the Coulomb charging effects of
the two dots, were measured using simultaneous detection and compared with
numerical simulations.


title: Noise components from black-hole binaries in our galaxy

abstract:
  Accreting binaries containing a black hole are stellar systems composed of a
normal star and a black hole. Because of the strong gravitational pull of the
black hole, matter is removed from the companion star and falls into the
compact ob ject. In falling, it forms an accretion disk of gas that spirals
towards the center, heating up and emitting in X rays. The physics of such a
structure is extremely complex and can be studied through observations with
X-ray satellites. The time series derived from X-ray observations of bright
black-hole binaries in the Galaxy show a complex phenomenology. Broad noise
components with a variability of up to 40% are observed, as well as
quasi-periodic features on time scales from 100 seconds down to a few
milliseconds. The characteristic frequencies of the different components can
change on very short time scales. However, some of these signals are elusive as
they are very weak and are drowned in intrinsic and instrumental noise. The
physical nature of these signals is still largely unknown, but it is clear that
they originate from gas orbiting a few kilometers from the central black hole
and accreting onto it. In addition of being important for the study of the
accretion of matter onto a black hole, these observational properties
constitute a unique probe for testing General Relativity in the strong field
regime. I review the current observational status as well as the techniques
used to study these signals.


title:
A new approach to solve the Boltzmann-Langevin equation for fermionic
  systems

abstract:
  We present a new method to introduce phase-space fluctuations in transport
theories, corresponding to a full implementation of the Boltzmann-Langevin
equation for fermionic systems. It is based on the procedure originally
developed by Bauer et al. for transport codes employing the test particle
method. In the new procedure, the Pauli principle is carefully checked, leading
to a good reproduction of the correct fluctuations in the ``continuum limit''
($h \to 0$). Accurate tests are carried out in one and two dimensional
idealized systems, and finally results for a full 3D application are shown. We
stress the reliability of this method, which can be easily plugged into
existing tranport codes using test particles, and its general applicability to
systems characterized by instabilities, like for instance multifragmentation
processes.


title:
The obstacle problem for nonlinear elliptic equations with variable
  growth and L^1-data

abstract:
  The aim of this paper is twofold: to prove, for L^1-data, the existence and
uniqueness of an entropy solution to the obstacle problem for nonlinear
elliptic equations with variable growth, and to show some convergence and
stability properties of the corresponding coincidence set. The latter follow
from extending the Lewy--Stampacchia inequalities to the general framework of
L^1.


title: Creation and Manipulation of Anyons in the Kitaev Model

abstract:
  We analyze the effect of local spin operators in the Kitaev model on the
honeycomb lattice. We show, in perturbation around the isolated-dimer limit,
that they create Abelian anyons together with fermionic excitations which are
likely to play a role in experiments. We derive the explicit form of the
operators creating and moving Abelian anyons without creating fermions and show
that it involves multi-spin operations. Finally, the important experimental
constraints stemming from our results are discussed.


title: Positive streamers in ambient air and a N2:O2-mixture (99.8 : 0.2)

abstract:
  Photographs show distinct differences between positive streamers in air or in
a nitrogen-oxygen mixture (0.2% O2). The streamers in the mixture branch more
frequently, but the branches also extinguish more easily. Probably related to
that, the streamers in the mixture propagate more in a zigzag manner while they
are straighter in air. Furthermore, streamers in the mixture can become longer;
they are thinner and more intense.


title: Pion and Kaon Spectra from Distributed Mass Quark Matter

abstract:
  After discussing some hints for possible masses of quasiparticles in quark
matter on the basis of lattice equation of state, we present pion and kaon
transverse spectra obtained by recombining quarks with distributed mass and
thermal cut power-law momenta as well as fragmenting by NLO pQCD with intrinsic
$k_T$ {and nuclear} broadening.


title: A generalized Fourier inversion theorem

abstract:
  In this work we define operator-valued Fourier transforms for suitable
integrable elements with respect to the Plancherel weight of a (not necessarily
Abelian) locally compact group. Our main result is a generalized version of the
Fourier inversion Theorem for strictly-unconditionally integrable Fourier
transforms. Our results generalize and improve those previously obtained by Ruy
Exel in the case of Abelian groups.


title: Bethe ansatz and Isomonodromic deformations

abstract:
  We study symmetries of the Bethe equations for the Gaudin model appeared
naturally in the framework of the geometric Langlands correspondence under the
name of Hecke operators and under the name of Schlesinger transformations in
the theory of isomonodromic deformations, and particularly in the theory of
Painlev\'e transcendents.


title:
Purely orbital diamagnetic to paramagnetic fluctuation of quasi
  two-dimensional carriers under in-plane magnetic field

abstract:
  An external magnetic field, $H$, applied parallel to a quasi two-dimensional
system modifies quantitatively and qualitatively the density of states. Using a
self-consistent numerical approach, we study how this affects the entropy, $S$,
the free energy, $F$, and the magnetization, $M$, for different sheet carrier
concentrations, $N_s$. As a prototype system we employ III-V double quantum
wells. We find that although $M$ is mainly in the opposite direction of $H$,
the system is not linear. Surprisingly $\partial M / \partial H$ swings between
negative and positive values, i.e., we predict an entirely orbital diamagnetic
to paramagnetic fluctuation. This phenomenon is important compared to the ideal
de Haas-van Alphen effect i.e. the corresponding phenomenon under perpendicular
magnetic field.


title:
Absolute continuity and singularity of two probability measures on a
  filtered space

abstract:
  Let $\mu$ and $\nu$ be fixed probability measures on a filtered space
$(\Omega, {\cal F}, ({\cal F}_t)_{t\in {\bf R}^{+}})$. Denote by $\mu_T $ and
$\nu_T $ (respectively, $\mu_{T-} $ and $\nu_{T-} $) the restrictions of the
measures $\mu$ and $\nu$ on ${\cal F}_T $ (respectively, on ${\cal F}_{T-} $)
for a stopping time $T$. We find the Hahn decomposition of $\mu_T $ and $\nu_T
$ using the Hahn decomposition of the measures $\mu$, $\nu$, and the Hellinger
process $h_t$ in the strict sense of order 1/2. The norm of the absolutely
continuous component of $\mu_{T-} $ with respect to $\nu_{T-} $ is computed in
terms of density processes and Hellinger integrals.


title: Long-Range Order in Electronic Transport through Disordered Metal Films

abstract:
  Ultracold atom magnetic field microscopy enables the probing of current flow
patterns in planar structures with unprecedented sensitivity. In
polycrystalline metal (gold) films we observe long-range correlations forming
organized patterns oriented at +/- 45 deg relative to the mean current flow,
even at room temperature and at length scales orders of magnitude larger than
the diffusion length or the grain size. The preference to form patterns at
these angles is a direct consequence of universal scattering properties at
defects. The observed amplitude of the current direction fluctuations scales
inversely to that expected from the relative thickness variations, the grain
size and the defect concentration, all determined independently by standard
methods. This indicates that ultracold atom magnetometry enables new insight
into the interplay between disorder and transport.


title: Geometry and scaling of cosmic voids

abstract:
  CONTEXT: Cosmic voids are observed in the distribution of galaxies and, to
some extent, in the dark matter distribution. If these distributions have
fractal geometry, it must be reflected in the geometry of voids; in particular,
we expect scaling sizes of voids. However, this scaling is not well
demonstrated in galaxy surveys yet. AIMS: Our objective is to understand the
geometry of cosmic voids in relation to a fractal structure of matter. We
intend to distinguish monofractal voids from multifractal voids, regarding
their scaling properties. We plan to analyse voids in the distributions of mass
concentrations (halos) in a multifractal and their relation to galaxy voids.
METHODS: We make a statistical analysis of point distributions based on the
void probability function and correlation functions. We assume that voids are
spherical and devise a simple spherical void finder. For continuous mass
distributions, we employ the methods of fractal geometry. We confirm the
analytical predictions with numerical simulations. Smoothed mass distributions
are suitable for the method of excursion sets. RESULTS: Voids are very
nonlinear and non-perturbative structures. Voids reflect the fractal geometry
of the matter distribution but not always directly: scaling sizes of voids
imply fractal geometry, but fractal voids may have a complicated geometry and
may not have scaling sizes. Proper multifractal voids are of this type. A
natural multifractal biasing model implies that the voids in the galaxy
distribution inherit the same complicated geometry. CONCLUSIONS: Current galaxy
surveys as well as cosmological N-body simulations indicate that cosmic voids
are proper multifractal voids. This implies the presence in the voids of
galaxies or, at least, small dark matter halos.


title: Weyl groups and Elliptic Solutions of the WDVV equations

abstract:
  A functional ansatz is developed which gives certain elliptic solutions of
the Witten-Dijkgraaf-Verlinde-Verlinde (or WDVV) equation. This is based on the
elliptic trilogarithm function introduced by Beilinson and Levin. For this to
be a solution results in a number of purely algebraic conditions on the set of
vectors that appear in the ansatz, this providing an elliptic version of the
idea, introduced by Veselov, of a V-system.
  Rational and trigonometric limits are studied together with examples of
elliptic V-systems based on various Weyl groups. Jacobi group orbit spaces are
studied: these carry the structure of a Frobenius manifold. The corresponding
almost dual structure is shown, in the A_N and B_N and conjecturally for an
arbitrary Weyl group, to correspond to the elliptic solutions of the WDVV
equations.
  Transformation properties, under the Jacobi group, of the elliptic
trilogarithm are derived together with various functional identities which
generalize the classical Frobenius-Stickelburger relations.


title:
Dynamic properties of quantum spin chains: Simple route to complex
  behavior

abstract:
  We examine dynamic structure factors of spin-1/2 chains with nearest-neighbor
interactions of XX and Dzyaloshinskii-Moriya type, and with periodic and random
changes in the sign of these interactions. This special kind of inhomogeneity
can be eliminated from the Hamiltonian by suitable transformation of the spin
variables. As a result, the dynamic structure factors of periodic or random
chains can be computed from those of the uniform chains. Using the exact
analytical and precise numerical results available for the uniform systems we
illustrate the effects of regular alternation or random disorder on dynamic
structure factors of quantum spin chains.


title:
Constraints on fall-back disks in radio pulsars and anomalous X-ray
  pulsars

abstract:
  Calculations have been made of fall-back disk heating by the pulsar wind as
distinct from the soft X-rays emitted by the neutron-star surface. The relation
between these heating rates and measured near-infrared fluxes in the K and Ks
bands places severe constraints on the inner radii of any fall-back disks that
may be present in radio pulsars and in some anomalous X-ray pulsars. The lower
limits found are so large that the disks concerned can have no significant
effect on pulsar spin-down.


title:
Studying accreting black holes and neutron stars with time series:
  beyond the power spectrum

abstract:
  The fluctuating brightness of cosmic X-ray sources, particularly accreting
black holes and neutron star systems, has enabled enormous progress in
understanding the physics of turbulent accretion flows, the behaviour of matter
on the surfaces of neutron stars and improving the evidence for black holes.
Most of this progress has been made by analysing and modelling time series data
in terms of their power and cross spectra, as will be discussed in other
articles in this volume. Recently, attempts have been made to make use of other
aspects of the data, by testing for non-linearity, non-Gaussianity, time
asymmetry and by examination of higher order Fourier spectra. These projects,
which have been made possible by the vast increase in data quality and quantity
over the past decade, are the subject of this article.


title: Gravitational vacuum polarization as an alternative to dark matter

abstract:
  It is assumed that the quantum vacuum may be studied as consisting of two
contributions, with positive and negative energy respectively, which interact
but slightly and may be displaced from each other. Then it is proposed that
dark matter may be just an increase of the quantum vacuum energy, with respect
to the normal dark energy level, induced by the gravitational field of galaxies
or clusters. A simple model is worked out able to reproduce astronomical
observations.


title: GRB-triggered searches for gravitational waves in LIGO data

abstract:
  The LIGO gravitational wave detectors have recently reached their design
sensitivity and finished a two-year science run. During this period one year of
data with unprecedented sensitivity has been collected. I will briefly describe
the status of the LIGO detectors and the overall quality of the most recent
science run. I also will present results of a search for inspiral waveforms in
gravitational wave data coincident with the short gamma ray burst detected on
1st February 2007, with its sky location error box overlapping a spiral arms of
M31. No gravitational wave signals were detected and a binary merger in M31 can
be excluded at the 99% confidence level.


title: Mutually Unbiased Bases for Continuous Variables

abstract:
  The concept of mutually unbiased bases is studied for N pairs of continuous
variables. To find mutually unbiased bases reduces, for specific states related
to the Heisenberg-Weyl group, to a problem of symplectic geometry. Given a
single pair of continuous variables, three mutually unbiased bases are
identified while five such bases are exhibited for two pairs of continuous
variables. For N = 2, the golden ratio occurs in the definition of these
mutually unbiased bases suggesting the relevance of number theory not only in
the finite-dimensional setting.


title: On the divergences of inflationary superhorizon perturbations

abstract:
  We discuss the infrared divergences that appear to plague cosmological
perturbation theory. We show that within the stochastic framework they are
regulated by eternal inflation so that the theory predicts finite fluctuations.
Using the $\Delta N$ formalism to one loop, we demonstrate that the infrared
modes can be absorbed into additive constants and the coefficients of the
diagrammatic expansion for the connected parts of two and three-point functions
of the curvature perturbation. As a result, the use of any infrared cutoff
below the scale of eternal inflation is permitted, provided that the background
fields are appropriately redefined. The natural choice for the infrared cutoff
would of course be the present horizon; other choices manifest themselves in
the running of the correlators. We also demonstrate that it is possible to
define observables that are renormalization group invariant. As an example, we
derive a non-perturbative, infrared finite and renormalization point
independent relation between the two-point correlators of the curvature
perturbation for the case of the free single field.


title: Phase diagram of a bosonic ladder with two coupled chains

abstract:
  We study a bosonic ladder with two coupled chains using the finite size
density matrix renormalisation group method. We show that in a commensurate
bosonic ladder the critical on-site interaction ($U_C$) for the superfluid to
Mott insulator transition becomes larger as the inter-chain hopping
($t_\bot$)increases. We analyze this quantum phase transition and obtain the
phase diagram in the $t_\bot -U$ plane.


title: On bounded solutions of a problem of R. Schilling

abstract: The paper deals with locally bounded solutions of a Schilling's problem.


title: Gravitational Wave Constraints on Multi-Brane Inflation

abstract:
  A class of non-canonical inflationary models is identified, where the
leading-order contribution to the non-Gaussianity of the curvature perturbation
is determined by the sound speed of the fluctuations in the inflaton field.
Included in this class of models is the effective action for multiple
coincident branes in the finite n limit. The action for this configuration is
determined using a powerful iterative technique, based upon the fundamental
representation of SU(2). In principle the upper bounds on the tensor-scalar
ratio that arise in the standard, single-brane DBI inflationary scenario can be
relaxed in such multi-brane configurations if a large and detectable
non-Gaussianity is generated. Moreover models with a small number of coincident
branes could generate a gravitational wave background that will be observable
to future experiments.


title:
Spectral energy distributions and high-energy emission of BL Lac type
  objects

abstract:
  Based on identifications from the Veron and Quasars.org catalogs, we
determine the optical-to-X-ray spectral indices for a sample of 201 BL Lac type
objects (BLLs) and search for trends in the distribution of these indices of
the sources detected in high-energy bands. We find that EGRET-detected sources
are low-energy peaked and that the positional correlation with the arrival
directions of ultra-high-energy cosmic rays from the previously studied AGASA,
Yakutsk and High Resolution Fly's Eye samples is dominated by low-energy-peaked
BLLs.


title: A Modified ICA Approach for Signal Separation in CMB Maps

abstract:
  AIMS: One of the most challenging and important problem of digital signal
processing in Cosmology is the separation of foreground contamination from
cosmic microwave background (CMB). This problem becomes even more difficult in
situations, as the CMB polarization observations, where the amount of available
"a priori" information is limited. In this case, it is necessary to resort to
the "blind separation" methods. One important member of this class is
represented by the "Independent Components Analysis" (ICA). In its original
formulation, this method has various interesting characteristics, but also some
limits. One of the most serious is the difficulty to take into account any
information available in advance. In particular, ICA is not able to exploit the
fact that emission of CMB is the same at all the frequencies of observations.
Here, we show how to deal with this question. The connection of the proposed
methodology with the "Internal Linear Composition" (ILC) technique is also
illustrated.
  METHODS: A modification of the classic ICA approach is presented and its
characteristics are analyzed both analytically and by means of numerical
experiments.
  RESULTS: The modified version of ICA appears to provide more stable results
and of better quality.


title:
Contribution of nano-scale effects to the total efficiency of converters
  of thermal neutrons on the basis of gadolinium foils

abstract:
  We study the influence of nano-scale layers of converters made from natural
gadolinium and its 157 isotope into the total efficiency of registration of
thermal neutrons. Our estimations show that contribution of low-energy Auger
electrons with the runs about nanometers in gadolinium, to the total efficiency
of neutron converters in this case is essential and results in growth of the
total efficiency of converters. The received results are in good consent to the
experimental data.


title:
On the local energy decay of solutions of the Dirac equation in the
  non-extreme Kerr-Newman metric, I

abstract:
  We investigate the local energy decay of solutions of the Dirac equation in
the non-extreme Kerr-Newman metric. First, we write the Dirac equation as a
Cauchy problem and define the Dirac operator. It is shown that the Dirac
operator is selfadjoint in a suitable Hilbert space. With the RAGE theorem, we
show that for each particle its energy located in any compact region outside of
the event horizon of the Kerr-Newman black hole decays in the time mean.


title: Self-Control of Traffic Lights and Vehicle Flows in Urban Road Networks

abstract:
  Based on fluid-dynamic and many-particle (car-following) simulations of
traffic flows in (urban) networks, we study the problem of coordinating
incompatible traffic flows at intersections. Inspired by the observation of
self-organized oscillations of pedestrian flows at bottlenecks [D. Helbing and
P. Moln\'ar, Phys. Eev. E 51 (1995) 4282--4286], we propose a self-organization
approach to traffic light control. The problem can be treated as multi-agent
problem with interactions between vehicles and traffic lights. Specifically,
our approach assumes a priority-based control of traffic lights by the vehicle
flows themselves, taking into account short-sighted anticipation of vehicle
flows and platoons. The considered local interactions lead to emergent
coordination patterns such as ``green waves'' and achieve an efficient,
decentralized traffic light control. While the proposed self-control adapts
flexibly to local flow conditions and often leads to non-cyclical switching
patterns with changing service sequences of different traffic flows, an almost
periodic service may evolve under certain conditions and suggests the existence
of a spontaneous synchronization of traffic lights despite the varying delays
due to variable vehicle queues and travel times. The self-organized traffic
light control is based on an optimization and a stabilization rule, each of
which performs poorly at high utilizations of the road network, while their
proper combination reaches a superior performance. The result is a considerable
reduction not only in the average travel times, but also of their variation.
Similar control approaches could be applied to the coordination of logistic and
production processes.


title: The orbital period of the eclipsing dwarf nova CG Draconis

abstract:
  We have performed time resolved photometry on the dwarf nova CG Dra and have
established for the first time that it is an eclipsing system. By measuring the
times of the eclipses, we determined the orbital period as 0.18864(4) d, or 4h
31m 38 +/- 3s. This value is consistent with the shorter of two periods
proposed from earlier spectroscopic studies. The orbital period places CG Dra
above the period gap. The symmetrical eclipses are of short duration (FWHM
18+/-2 min, or 0.066(7) of the orbital period) and shallow (average 0.16+/-0.02
mag), suggesting a grazing eclipse which is consistent with an orbital
inclination just above the critical value. Flickering persists through the
eclipse which means that the flickering source is not occulted by the secondary
star.


abstract:
  In this paper, we study CAT(0) groups and Coxeter groups whose boundaries are
scrambled sets. Suppose that a group $G$ acts geometrically (i.e. properly and
cocompactly by isometries) on a CAT(0) space $X$. (Such group $G$ is called a
{\it CAT(0) group}.) Then the group $G$ acts by homeomorphisms on the boundary
$\partial X$ of $X$ and we can define a metric $d_{\partial X}$ on the boundary
$\partial X$. The boundary $\partial X$ is called a {\it scrambled set} if for
any $\alpha,\beta\in\partial X$ with $\alpha\neq\beta$, (1)
$\limsup\{d_{\partial X}(g\alpha,g\beta) | g\in G\}>0$ and (2)
$\liminf\{d_{\partial X}(g\alpha,g\beta) | g\in G\}=0$. We investigate when are
boundaries of CAT(0) groups (and Coxeter groups) scrambled sets.


title:
On the role of ergodicity and mixing in the central limit theorem for
  Casati-Prosen triangle map variables

abstract:
  In this manuscript we analyse the behaviour of the probability density
function of the sum of $N$ deterministic variables generated from the triangle
map of Casati-Prosen. For the case in which the map is both ergodic and mixing
the resulting probability density function quickly concurs with the Normal
distribution. When these properties are modified the resulting probability
density functions are described by power-laws. Moreover, contrarily to what it
would be expected, as the number of added variables $N$ increases the distance
to Gaussian distribution increases. This behaviour goes against standard
central limit theorem. By extrapolation of our finite size results we preview
that in the limit of $N$ going to infinity the distribution has the same
asymptotic decay as a Lorenztian (or a $q=2$-Gaussian).


title: Electron delocalization in bilayer graphene induced by an electric field

abstract:
  Electronic localization is numerically studied in disordered bilayer graphene
with an electric-field induced energy gap. Bilayer graphene is a zero-gap
semiconductor, in which an energy gap can be opened and controlled by an
external electric field perpendicular to the layer plane. We found that, in the
smooth disorder potential not mixing the states in different valleys (K and K'
points), the gap opening causes a phase transition at which the electronic
localization length diverges. We show that this can be interpreted as the
integer quantum Hall transition at each single valley, even though the magnetic
field is absent.


title:
Higher Twist Contributions to the Structure Functions F_2^p(x,Q^2) and
  F_2^d(x,Q^2) at Large x and Higher Orders

abstract:
  The higher twist contributions to the deeply inelastic structure functions
$F_2^{p}(x,Q^2)$ and $F_2^{d}(x,Q^2)$ for larger values of the Bjorken variable
$x$ are extracted extrapolating the {twist--2} contributions measured in the
large $W^2$ region to the region $4 \GeV^2 \leq W^2 \leq 12.5 \GeV^2$ applying
target mass corrections. We compare the results for the NLO, NNLO and N$^3$LO
analyzes and include also the large $x$ at N$^4$LO to the Wilson coefficients.
A gradual lowering of the higher twist contributions going from NLO to N$^4$LO
is observed, which stresses the importance of higher order corrections.


title:
Generalised energy conservation law for the wave equations with variable
  propagation speed

abstract:
  We investigate the long time behaviour of the $L^2$-energy of solutions to
wave equations with variable speed. The novelty of the approach is the
combination of estimates for higher order derivatives of the coefficient with a
stabilisation property.


title:
The effective action of the heterotic string compactified on manifolds
  with SU(3) structure

abstract:
  We derive the N=1 effective action of the heterotic string compactified on
manifolds with SU(3) structure in the presence of background fluxes. We use a
Kaluza-Klein reduction and compute the moduli dependence of the Kaehler
potential, the gauge kinetic function and the superpotential entirely from
fermionic terms of the reduced action.


title: Maximal Quantum Violation of the CGLMP Inequality on Its Both Sides

abstract:
  We investigate the maximal violations for both sides of the $d$-dimensional
CGLMP inequality by using the Bell operator method. It turns out that the
maximal violations have a decelerating increase as the dimension increases and
tend to a finite value at infinity. The numerical values are given out up to
$d=10^6$ for positively maximal violations and $d=2\times 10^5$ for negatively
maximal violations. Counterintuitively, the negatively maximal violations tend
to be a little stronger than the positively maximal violations. Further we show
the states corresponding to these maximal violations and compare them with the
maximally entangled states by utilizing entangled degree defined by von Neumann
entropy. It shows that their entangled degree tends to some nonmaximal value as
the dimension increases.


title:
Global spectral energy distribution of the Crab Nebula in the prospect
  of the Planck satellite polarisation calibration

abstract:
  Whithin the framework of the Planck satellite polarisation calibration, we
present a study of the Crab Nebula spectral energy distribution (SED) over more
than 6 decades in frequency ranging from 1 to $\rm 10^6 GHz$. The Planck
satellite mission observes the sky from 30 to 857 GHz and therefore we focus on
the millimetre region. We use radio and submillimetre data from the WMAP
satellite between 23 and 94 GHz (from 13 to 3.18 mm) and from the Archeops
balloon experiment between 143 (2.1 mm) and 545 GHz (0.55 mm), and a compendium
of other Crab Nebula observations. The Crab SED is compared to models including
three main components : synchrotron which is responsible for the emission at
low and at high frequencies, dust which explains the excess of flux observed by
the IRAS satellite and an extra component on the millimetre regime. From this
analysis we conclude that the unpolarised emission of the Crab Nebula at
microwave and millimetre wavelengths is the same synchrotron emission that the
one observed in the radio domain. Therefore, we expect the millimetre emission
of the Crab nebula to be polarised with the same degree of polarisation and
orientation than the radio emission. We set upper limits on the possible errors
induced by any millimetre extra component on the reconstruction of the degree
and angle of polarisation at the percent level as a maximum. This result
strongly supports the choice by the Planck collaboration of the Crab nebula
emission for performing polarisation cross-checks in the range 30 (299 mm) to
353 GHz (0.849 mm).


title: Nanomechanical properties of few-layer graphene membranes

abstract:
  We have measured the mechanical properties of few-layer graphene and graphite
flakes that are suspended over circular holes. The spatial profile of the
flake's spring constant is measured with an atomic force microscope. The
bending rigidity of and the tension in the membranes are extracted by fitting a
continuum model to the data. For flakes down to eight graphene layers, both
parameters show a strong thickness-dependence. We predict fundamental resonance
frequencies of these nanodrums in the GHz range based on the measured bending
rigidity and tension.


title: The exit problem in optimal non-causal extimation

abstract:
  We study the phenomenon of loss of lock in the optimal non-causal phase
estimation problem, a benchmark problem in nonlinear estimation. Our method is
based on the computation of the asymptotic distribution of the optimal
estimation error in case the number of trajectories in the optimization problem
is finite. The computation is based directly on the minimum noise energy
optimality criterion rather than on state equations of the error, as is the
usual case in the literature. The results include an asymptotic computation of
the mean time to lose lock (MTLL) in the optimal smoother. We show that the
MTLL in the first and second order smoothers is significantly longer than that
in the causal extended Kalman filter.


title:
Comparison of fragment partitions production in peripheral and central
  collisions

abstract:
  Ensembles of single-source events, produced in peripheral and central
collisions and correponding respectively to quasi-projectile and quasi-fusion
sources, are analyzed. After selections on fragment kinematic properties,
excitation energies of the sources are derived using the calorimetric method
and the mean behaviour of fragments of the two ensembles are compared.
Differences observed in their partitions, especially the charge asymmetry, can
be related to collective energy deposited in the systems during the collisions.


title: Modeling kicks from the merger of generic black-hole binaries

abstract:
  Recent numerical relativistic results demonstrate that the merger of
comparable-mass spinning black holes has a maximum ``recoil kick'' of up to
$\sim 4000 \kms$. However the scaling of these recoil velocities with mass
ratio is poorly understood. We present new runs showing that the maximum
possible kick perpendicular to the orbital plane does not scale as $\sim\eta^2$
(where $\eta$ is the symmetric mass ratio), as previously proposed, but is more
consistent with $\sim\eta^3$, at least for systems with low orbital precession.
We discuss the effect of this dependence on galactic ejection scenarios and
retention of intermediate-mass black holes in globular clusters.


title: On principal hook length partitions and durfee sizes in skew characters

abstract:
  In this paper we construct for a given arbitrary skew diagram A all
partitions nu with maximal principal hook lengths among all partitions with the
character [nu] appearing in the skew character [A]. Furthermore we show that
these are also partitions with minimal Durfee size. This we use to give the
maximal Durfee size for [nu] appearing in [A] for the cases when A decays into
two partitions and for some special cases of A. Also this gives conditions for
two skew diagrams to represent the same skew character.


title: 3D meshfree magnetohydrodynamics

abstract:
  We describe a new method to include magnetic fields into smooth particle
hydrodynamics. The derivation of the self-gravitating hydrodynamics equations
from a variational principle is discussed in some detail. The non-dissipative
magnetic field evolution is instantiated by advecting so-called Euler
potentials. This approach enforces the crucial
$\nabla\cdot\vec{B}=0$-constraint by construction. These recent developments
are implemented in our three-dimensional, self-gravitating magnetohydrodynamics
code MAGMA. A suite of tests is presented that demonstrates the superiority of
this new approach in comparison to previous implementations.


title:
Hyperaccretion after the Blandford-Znajek Process: a New Model for GRBs
  with X-Ray Flares Observed in Early Afterglows

abstract:
  We propose a three-stage model with Blandford-Znajek (BZ) and hyperaccretion
process to interpret the recent observations of early afterglows of Gamma-Ray
Bursts (GRBs). In the first stage, the prompt GRB is powered by a rotating
black hole (BH) invoking the BZ process. The second stage is a quiet stage, in
which the BZ process is shut off, and the accretion onto the BH is depressed by
the torque exerted by the magnetic coupling (MC) process. Part of the
rotational energy transported by the MC process from the BH is stored in the
disk as magnetic energy. In the third stage, the MC process is shut off when
the magnetic energy in the disk accumulates and triggers the magnetic
instability. At this moment, the hyperaccretion process may onset, and the jet
launched in this restarted central engine generates the observed X-ray flares.
This model can account for energies and timescales of GRBs with X-ray flares
observed in early afterglows.


title: On nondegeneracy of curves

abstract:
  A curve is called nondegenerate if it can be modeled by a Laurent polynomial
that is nondegenerate with respect to its Newton polytope. We show that up to
genus 4, every curve is nondegenerate. We also prove that the locus of
nondegenerate curves inside the moduli space of curves of fixed genus g > 1 is
min(2g+1,3g-3)-dimensional, except in case g=7 where it is 16-dimensional.


title: Avalanches of Activation and Spikes in Neuronal Complex Networks

abstract:
  As shown recently (arXiv:0801.3056), several types of neuronal complex
networks involving non-linear integration-and-fire dynamics exhibit an abrupt
activation along their transient regime. Interestingly, such an avalanche of
activation has also been found to depend strongly on the topology of the
networks: while the Erd\H{o}s-R\'eny, Barab\'asi-Albert, path-regular and
path-transformed BA models exhibit well-defined avalanches; Watts-Strogatz and
geographical structures present instead a gradual dispersion of activation
amongst their nodes. The current work investigates such phenomena by
considering a mean-field equivalent model of a network which is strongly
founded on the concepts of concentric neighborhoods and degrees. It is shown
that the hierarchical number of nodes and hierarchical degrees define the
intensity and timing of the avalanches. This approach also allowed the
identification of the beginning activation times during the transient dynamics,
which is particularly important for community identification (arXiv:0801.4269,
arXiv:0801.4684). The main concepts and results in this work are illustrated
with respect to theoretical and real-world (\emph{C. elegans}) networks.
Several results are reported, including the identification of secondary
avalanches, the validation of the equivalent model, the identification of the
possible universality of the avalanches for most networks (depending only on
the network size), as well as the identification of the fact that different
avalanches can be obtained by locating the activation source at different
neurons of the \emph{C. elegans} network.

categories: physics.soc-ph cond-mat.dis-nn physics.comp-ph q-bio.NC


title:
Adiabatic charge and spin pumping through quantum dots with
  ferromagnetic leads

abstract:
  We study adiabatic pumping of electrons through quantum dots attached to
ferromagnetic leads. Hereby we make use of a real-time diagrammatic technique
in the adiabatic limit that takes into account strong Coulomb interaction in
the dot. We analyze the degree of spin polarization of electrons pumped from a
ferromagnet through the dot to a nonmagnetic lead (N-dot-F) as well as the
dependence of the pumped charge on the relative leads' magnetization
orientations for a spin-valve (F-dot-F) structure. For the former case, we find
that, depending on the relative coupling strength to the leads, spin and charge
can, on average, be pumped in opposite directions. For the latter case, we find
an angular dependence of the pumped charge, that becomes more and more
anharmonic for large spin polarization in the leads.


title: Approximability Distance in the Space of H-Colourability Problems

abstract:
  A graph homomorphism is a vertex map which carries edges from a source graph
to edges in a target graph. We study the approximability properties of the
Weighted Maximum H-Colourable Subgraph problem (MAX H-COL). The instances of
this problem are edge-weighted graphs G and the objective is to find a subgraph
of G that has maximal total edge weight, under the condition that the subgraph
has a homomorphism to H; note that for H=K_k this problem is equivalent to MAX
k-CUT. To this end, we introduce a metric structure on the space of graphs
which allows us to extend previously known approximability results to larger
classes of graphs. Specifically, the approximation algorithms for MAX CUT by
Goemans and Williamson and MAX k-CUT by Frieze and Jerrum can be used to yield
non-trivial approximation results for MAX H-COL. For a variety of graphs, we
show near-optimality results under the Unique Games Conjecture. We also use our
method for comparing the performance of Frieze & Jerrum's algorithm with
Hastad's approximation algorithm for general MAX 2-CSP. This comparison is, in
most cases, favourable to Frieze & Jerrum.


title: Structure and magnetic properties of the Ho2Ge2O7 pyrogermanate

abstract:
  We report the anisotropic magnetic properties of Ho2Ge2O7 determined from dc
and ac magnetization, specific heat and powder neutron diffraction experiments.
The magnetic lanthanide sublattice, seen in our refinement of the tetragonal
pyrogermanate crystal structure, is a right-handed spiral of edge-sharing and
corner-sharing triangles; the local Ho-O coordination indicates that the
crystal field is anisotropic. Susceptibility and magnetization data indeed show
that the magnetism is highly anisotropic, and the magnetic structure has the Ho
moments confined to the plane perpendicular to the structural spiral. The
ordered moment of Ho3+, as determined from refinement of the neutron
diffraction data, is 9.0 mu_B. Magnetic ordering occurs around 1.6 K.
Temperature and field dependent ac susceptibility measurements show that this
compound displays spin relaxation phenomena analogous to what is seen in the
spin ice pyrochlore system Ho2Ti2O7.


title: Macroelement modeling of shallow foundations

abstract:
  The paper presents a new macroelement model for shallow foundations. The
model is defined through a non-linear constitutive law written in terms of some
generalized force and displacement parameters. The linear part of this
constitutive law comes from the dynamic impedances of the foundation. The
non-linear part comprises two mechanisms. One is due to the irreversible
elastoplastic soil behavior: it is described with a bounding surface
hypoplastic model, adapted for the description of the cyclic soil response. An
original feature of the formulation is that the bounding surface is considered
independently of the surface of ultimate loads of the system. The second
mechanism is the detachment that can take place at the soil-footing interface
(foundation uplift). It is totally reversible and non-dissipative and can thus
be described by a phenomenological non-linear elastic model. The macroelement
is qualitatively validated by application to soil-structure interaction
analyses of simple real structures.


title:
Une note \`a propos du Jacobien de $n$ fonctions holomorphes \`a
  l'origine de $\mathbb{C}^n$

abstract:
  Let $f_1,...,f_n$ be $n$ germs of holomorphic functions at the origin of
$\mathbb{C}^n$ such that $f_i(0)=0$, $1\leq i\leq n$. We give a proof based on
the J. Lipman's theory of residues via Hochschild Homology that the Jacobian of
$f_1,...,f_n$ belongs to the ideal generated by $f_1,...,f_n$ belongs to the
ideal generated by $f_1,...,f_n$ if and only if the dimension ot the germ of
common zeos of $f_1,...,f_n$ is sttrictly positive. In fact we prove much more
general results which are relatives versions of this result replacing the field
$\mathbb{C}$ by convenient noetherian rings $\mathbf{A}$ (c.f. Th. 3.1 and Th.
3.3). We then show a \L ojasiewicz inequality for the jacobian analogous to the
classical one by S. \L ojasiewicz for the gradient.


title: Anisotropy driven ultrafast nanocluster burrowing

abstract:
  We explore the occurrence of low-energy and low-temperature transient cluster
burrowing leading to intact cluster inclusions. In particular, the anomalously
fast (ballistic) Pt nanocluster implantation into Al and Ti substrates has been
found by molecular dynamics simulations using a tight-binding many-body
potential with the 1-5 eV/atom low impact energy. Similar behavior has also
been found for many other cluster/substrate couples such as Cu/Al and Ni/Ti,
Co/Ti, etc. In particular, in Ni/Ti at already $\sim 0.5$ eV/atom impact energy
burrowing takes place. At this few eV/atom low impact energy regime instead of
the expected stopping at the surface we find the propagation of the cluster
through a thin Al slab as thick as $\sim 50$ $\hbox{\AA}$ with a nearly
constant speed ($\propto 1$ eV/atom). Hence the cluster moves far beyond the
range of the impact energy which suggests that the mechanism of cluster
burrowing can not be explained simply by collisional cascade effects. In the
couples with reversed succession (e.g. Ti/Pt, Al/Pt) no burrowing has been
found, the clusters remain on the surface (the asymmetry of burrowing). We
argue that cluster penetration occurs at few eV/atom impact energy when the
cluster/substrate interaction is size-mismatched and mass anisotropic
atomically.


title: Rank and regularity for averages over submanifolds

abstract:
  This paper establishes endpoint $L^p-L^q$ and Sobolev mapping properties of
Radon-like operators which satisfy a homogeneity condition (similar to
semiquasihomogeneity) and a condition on the rank of a matrix related to
rotational curvature. For highly degenerate operators, the rank condition is
generically satisfied for algebraic reasons, similar to an observation of
Greenleaf, Pramanik, and Tang concerning oscillatory integral operators.


title: The distribution function of dark matter in massive haloes

abstract:
  We study the distribution function (DF) of dark matter particles in haloes of
mass range 10^{14}--10^{15}\Msun. In the numerical part of this work we measure
the DF for a sample of relaxed haloes formed in the simulation of a standard
\LambdaCDM model. The DF is expressed as a function of energy E and the
absolute value of the angular momentum L, a form suitable for comparison with
theoretical models. By proper scaling we obtain the results that do not depend
on the virial mass of the haloes. We demonstrate that the DF can be separated
into energy and angular momentum components and propose a phenomenological
model of the DF in the form
f_{E}(E)[1+L^{2}/(2L_{0}^{2})]^{-\beta_{\infty}+\beta_{0}}L^{-2\beta_{0}}. This
formulation involves three parameters describing the anisotropy profile in
terms of its asymptotic values (\beta_{0} and \beta_{\infty}) and the scale of
transition between them (L_{0}). The energy part f_{E}(E) is obtained via
inversion of the integral for spatial density. We provide a straightforward
numerical scheme for this procedure as well as a simple analytical
approximation for a typical halo formed in the simulation. The DF model is
extensively compared with the simulations: using the model parameters obtained
from fitting the anisotropy profile, we recover the DF from the simulation as
well as the profiles of the dispersion and kurtosis of radial and tangential
velocities. Finally, we show that our DF model reproduces the power-law
behaviour of phase space density Q=\rho(r)/\sigma^{3}(r).


title:
One-particle spectral properties of the t-J-$V$ model on the triangular
  lattice near charge order

abstract:
  We study the t-J-$V$ model beyond mean field level at finite doping on the
triangular lattice. The Coulomb repulsion $V$ between nearest neighbors brings
the system to a charge ordered state for $V$ larger than a critical value
$V_c$. One-particle spectral properties as self-energy, spectral functions and
the quasiparticle weight are studied near and far from the charge ordered
phase. When the system approaches the charge ordered state, charge fluctuations
become soft and they strongly influence the system leading to incoherent
one-particle excitations. Possible implications for cobaltates are given.


title: Autonomous software: Myth or magic?

abstract:
  We discuss work by the eSTAR project which demonstrates a fully closed loop
autonomous system for the follow up of possible micro-lensing anomalies. Not
only are the initial micro-lensing detections followed up in real time, but
ongoing events are prioritised and continually monitored, with the returned
data being analysed automatically. If the ``smart software'' running the
observing campaign detects a planet-like anomaly, further follow-up will be
scheduled autonomously and other telescopes and telescope networks alerted to
the possible planetary detection. We further discuss the implications of this,
and how such projects can be used to build more general autonomous observing
and control systems.


title:
Search for the Higgs boson in events with missing transverse energy and
  b quark jets produced in proton-antiproton collisions at s**(1/2)=1.96 TeV

abstract:
  We search for the standard model Higgs boson produced in association with an
electroweak vector boson in events with no identified charged leptons, large
imbalance in transverse momentum, and two jets where at least one contains a
secondary vertex consistent with the decay of b hadrons. We use ~1 fb-1
integrated luminosity of proton-antiproton collisions at s**(1/2)=1.96 TeV
recorded by the CDF II experiment at the Tevatron. We find 268 (16) single
(double) b-tagged candidate events, where 248 +/- 43 (14.4 +/- 2.7) are
expected from standard model background processes. We place 95% confidence
level upper limits on the Higgs boson production cross section for several
Higgs boson masses ranging from 110 GeV/c2 to 140 GeV/c2. For a mass of 115
GeV/c2 the observed (expected) limit is 20.4 (14.2) times the standard model
prediction.


title: A regional Bayesian POT model for flood frequency analysis

abstract:
  Flood frequency analysis is usually based on the fitting of an extreme value
distribution to the local streamflow series. However, when the local data
series is short, frequency analysis results become unreliable. Regional
frequency analysis is a convenient way to reduce the estimation uncertainty. In
this work, we propose a regional Bayesian model for short record length sites.
This model is less restrictive than the index flood model while preserving the
formalism of "homogeneous regions". The performance of the proposed model is
assessed on a set of gauging stations in France. The accuracy of quantile
estimates as a function of the degree of homogeneity of the pooling group is
also analysed. The results indicate that the regional Bayesian model
outperforms the index flood model and local estimators. Furthermore, it seems
that working with relatively large and homogeneous regions may lead to more
accurate results than working with smaller and highly homogeneous regions.


title: Parent Stars of Extrasolar Planets. IX. Lithium Abundances

abstract:
  We compare the Li abundances of a sample of stars with planets discovered
with the Doppler method to a sample of stars without detected planets. We
prepared the samples by combining the Li abundances reported in several recent
studies in a consistent way. Our results confirm recent claims that the Li
abundances of stars with planets are smaller than those of stars without
planets near the solar temperature. We also find that the vsini and $R^{'}_{\rm
HK}$ anomalies correlate with the Li abundance anomalies. These results suggest
that planet formation processes have altered the rotation and Li abundances of
stars that host Doppler detected planets. We encourage others to test these
findings with additional observations of Li in stars with temperatures between
5600 and 6200 K.


title: A predicted "Faraday oscillation" in photoexcited semiconductors

abstract:
  While, for semiconductors photoexcited by a circularly polarized pump, the
polarization plane of a linearly polarized probe has been shown to rotate, we
here predict a spectacular change when the pump beam is linearly polarized,
from Faraday rotation to Faraday oscillation, the oscillation of the
polarization plane going along a change of the photon polarization from linear
to elliptical. This effect, which reduces to zero when the probe field is
parallel or perpendicular to the pump field, comes from coherence between the
real excitons created by the pump and the virtual exciton coupled to the
unabsorbed probe, as easy to see from the Shiva diagrams which represent the
many-body physics taking place in this coupled photon-composite-exciton system.


title:
Modeling All Exceedances Above a Threshold Using an Extremal Dependence
  Structure: Inferences on Several Flood Characteristics

abstract:
  Flood quantile estimation is of great importance for many engineering studies
and policy decisions. However, practitioners must often deal with small data
available. Thus, the information must be used optimally. In the last decades,
to reduce the waste of data, inferential methodology has evolved from annual
maxima modeling to peaks over a threshold one. To mitigate the lack of data,
peaks over a threshold are sometimes combined with additional information -
mostly regional and historical information. However, whatever the extra
information is, the most precious information for the practitioner is found at
the target site. In this study, a model that allows inferences on the whole
time series is introduced. In particular, the proposed model takes into account
the dependence between successive extreme observations using an appropriate
extremal dependence structure. Results show that this model leads to more
accurate flood peak quantile estimates than conventional estimators. In
addition, as the time dependence is taken into account, inferences on other
flood characteristics can be performed. An illustration is given on flood
duration. Our analysis shows that the accuracy of the proposed models to
estimate the flood duration is related to specific catchment characteristics.
Some suggestions to increase the flood duration predictions are introduced.


title: A bilinear pseudodifferential calculus

abstract:
  In this paper, we are interested in the construction of a bilinear
pseudodifferential calculus. We define some symbolic classes which contains
those of Coifman-Meyer. These new classes allow us to consider operators
closely related to the bilinear Hilbert transform. We give a description of the
action of our bilinear operators on Sobolev spaces. These classes also have a
``nice'' behavior through the transposition and the composition operations that
we will present.


title: A quantum solution to the arrow-of-time dilemma

abstract:
  The arrow of time dilemma: the laws of physics are invariant for time
inversion, whereas the familiar phenomena we see everyday are not (i.e. entropy
increases). I show that, within a quantum mechanical framework, all phenomena
which leave a trail of information behind (and hence can be studied by physics)
are those where entropy necessarily increases or remains constant. All
phenomena where the entropy decreases must not leave any information of their
having happened. This situation is completely indistinguishable from their not
having happened at all. In the light of this observation, the second law of
thermodynamics is reduced to a mere tautology: physics cannot study those
processes where entropy has decreased, even if they were commonplace.


title: Exceptional sets for the derivatives of Blaschke products

abstract:
  We obtain growth estimates for the logarithmic derivative $B'(z)/B(z)$ of a
Blaschke product as $|z| \to 1$ and $z$ avoids some exceptional sets.


title:
Invariant differential operators and an infinite dimensional Howe-type
  correspondence. Part I: Structure of the associated algebras of differential
  operators

abstract:
  If $Q$ is a non degenerate quadratic form on ${\bb C}^n$, it is well known
that the differential operators $X=Q(x)$, $Y=Q(\partial)$, and
$H=E+\frac{n}{2}$, where $E$ is the Euler operator, generate a Lie algebra
isomorphic to ${\go sl}_{2}$. Therefore the associative algebra they generate
is a quotient of the universal enveloping algebra ${\cal U}({\go sl}_{2})$.
This fact is in some sense the foundation of the metaplectic representation.
The present paper is devoted to the study of the case where $Q(x)$ is replaced
by $\Delta_{0}(x)$, where $\Delta_{0}(x)$ is the relative invariant of a
prehomogeneous vector space of commutative parabolic type ($ {\go g},V $), or
equivalently where $\Delta_{0}$ is the "determinant" function of a simple
Jordan algebra $V$ over ${\bb C}$. In this Part I we show several structure
results for the associative algebra generated by $X=\Delta_{0}(x)$,
$Y=\Delta_{0}(\partial)$. Our main result shows that if we consider this
algebra as an algebra over a certain commutative ring ${\bf A}$ of invariant
differential operators it is isomorphic to the quotient of what we call a
generalized Smith algebra $S(f, {\bf A}, n)$ where $f\in {\bf A}[t]$. The Smith
algebras (over ${\bb C}$) were introduced by P. Smith as "natural"
generalizations of ${\cal U}({\go sl}_{2})$.


title: Line Searches in Swift X-ray Spectra

abstract:
  Prior to the launch of the Swift mission several X-ray line detections were
reported in Gamma Ray Burst afterglow spectra. To date, these pre-Swift era
results have not been conclusively confirmed. The most contentious issue in
this area is the choice of statistical method used to evaluate the significance
of these features. In this paper we compare three different methods already
extant in the literature for assessing the significance of possible line
features and discuss their relative advantages and disadvantages. The methods
are demonstrated by application to observations of 40 bursts from the archive
of Swift XRT at early times (< few ks post trigger in the rest frame of the
burst). Based on this thorough analysis we found no strong evidence for
emission lines. For each of the three methods we have determined detection
limits for emission line strengths in bursts with spectral parameters typical
of the Swift-era sample. We also discuss the effects of the current calibration
status on emission line detection.


title: The infinitesimal Hopf algebra and the poset of planar forests

abstract:
  We introduce an infinitesimal Hopf algebra of planar trees, generalising the
construction of the non-commutative Connes-Kreimer Hopf algebra. A
non-degenerate pairing and a dual basis are defined, and a combinatorial
interpretation of the pairing in terms of orders on the vertices of planar
forests is given. Moreover, the coproduct and the pairing can also be described
with the help of a partial order on the set of planar forests, making it
isomorphic to the Tamari poset. As a corollary, the dual basis can be computed
with a M\"obius inversion.


title:
Global Sensitivity Analysis of Stochastic Computer Models with joint
  metamodels

abstract:
  The global sensitivity analysis method, used to quantify the influence of
uncertain input variables on the response variability of a numerical model, is
applicable to deterministic computer code (for which the same set of input
variables gives always the same output value). This paper proposes a global
sensitivity analysis methodology for stochastic computer code (having a
variability induced by some uncontrollable variables). The framework of the
joint modeling of the mean and dispersion of heteroscedastic data is used. To
deal with the complexity of computer experiment outputs, non parametric joint
models (based on Generalized Additive Models and Gaussian processes) are
discussed. The relevance of these new models is analyzed in terms of the
obtained variance-based sensitivity indices with two case studies. Results show
that the joint modeling approach leads accurate sensitivity index estimations
even when clear heteroscedasticity is present.


title:
Usefulness of the Reversible Jump Markov Chain Monte Carlo Model in
  Regional Flood Frequency Analysis

abstract:
  Regional flood frequency analysis is a convenient way to reduce estimation
uncertainty when few data are available at the gauging site. In this work, a
model that allows a non-null probability to a regional fixed shape parameter is
presented. This methodology is integrated within a Bayesian framework and uses
reversible jump techniques. The performance on stochastic data of this new
estimator is compared to two other models: a conventional Bayesian analysis and
the index flood approach. Results show that the proposed estimator is
absolutely suited to regional estimation when only a few data are available at
the target site. Moreover, unlike the index flood estimator, target site index
flood error estimation seems to have less impact on Bayesian estimators. Some
suggestions about configurations of the pooling groups are also presented to
increase the performance of each estimator.


title: Non-commutative connections of the second kind

abstract:
  A connection-like objects, termed {\em hom-connections} are defined in the
realm of non-commutative geometry. The definition is based on the use of
homomorphisms rather than tensor products. It is shown that hom-connections
arise naturally from (strong) connections in non-commutative principal bundles.
The induction procedure of hom-connections via a map of differential graded
algebras or a differentiable bimodule is described. The curvature for a
hom-connection is defined, and it is shown that flat hom-connections give rise
to a chain complex.


title: Spectral properties of the BCS gap equation of superfluidity

abstract:
  We present a review of recent work on the mathematical aspects of the BCS gap
equation, covering our results of [arXiv:0801.4159] as well our recent joint
work with Hamza and Solovej [arXiv:math-ph/0703086] and with Frank and Naboko
[arXiv:0704.3564], respectively. In addition, we mention some related new
results.


title: String order and symmetries in quantum spin lattices

abstract:
  We show that the existence of string order in a given quantum state is
intimately related to the presence of a local symmetry by proving that both
concepts are equivalent within the framework of finitely correlated states.
Once this connection is established, we provide a complete characterization of
local symmetries in these states. The results allow to understand in a
straightforward way many of the properties of string order parameters, like
their robustness/fragility under perturbations and their typical disappearance
beyond strictly one-dimensional lattices. We propose and discuss an alternative
definition, ideally suited for detecting phase transitions, and generalizations
to two and more spatial dimensions.


title: Jack polynomials and free cumulants

abstract:
  We study the coefficients in the expansion of Jack polynomials in terms of
power sums. We express them as polynomials in the free cumulants of the
transition measure of an anisotropic Young diagram. We conjecture that such
polynomials have nonnegative integer coefficients. This extends recent results
about normalized characters of the symmetric group.