title: The total charm cross section

abstract:
  We assess the theoretical uncertainties on the total charm cross section. We
discuss the importance of the quark mass, the scale choice and the parton
densities on the estimate of the uncertainty. We conclude that due to the small
charm quark mass, which amplifies the effect of the other parameters in the
calculation, the uncertainty on the total charm cross section is difficult to
quantify.


title: On Weak Fields in Finsler Spaces

abstract:
  It is shown that in the weak field approximation the new geometrical approach
can lead to the linear field equations for the several independent fields. For
the stronger fields and in the second order approximation the field equations
become non-linear, and the fields become dependent. This breaks the
superposition principle for every separate field and produces the interaction
between different fields.The unification of the gravitational and
electromagnetic field theories is performed in frames of the geometrical
approach in the pseudo Riemannian space and in the curved Berwald-Moor space.


title: Host galaxy subtraction of TeV candidate BL Lacertae objects

abstract:
  We have derived R-band host galaxy fluxes of 20 TeV candidate BL Lacertae
objects as a function of aperture radius and FWHM. The results are given as
correction tables, that list the fluxes (in mJy) of all ``contaminating''
sources (host galaxy + significant nearby objects) as a function of aperture
radius and FWHM. We found that the derived fluxes depend strongly on aperture
radius, but the FWHM has only a minor effect (a few percent). We also discuss
the implications of our findings to optical monitoring programs and potential
sources of error in our derived fluxes. During this work we have also
constructed new calibration star sequences for 9 objects and present the
finding charts and calibrated magnitudes.


title:
Properties of the angular gap in a one dimensional photonic band gap
  structure containing single negative materials

abstract:
  The linear properties of the angular gap in a one dimensional photonic band
gap structure containing single negative material layers are investigated. This
gap forms at oblique incidence due to total internal reflection into air when
the Snell's law breaks down and its lower edge occurs at the frequency where
the refractive index of one or both layers of the structure approaches zero.
This gap is found to be highly sensitive to the incident angle and the
polarization of light, but is not affected by thickness ratio of the layers. It
is also shown that the electric field is extremely enhanced at the low
frequency edge of this gap for transverse magnetic polarization. This highly
enhanced electric field can be used for certain applications.


title: Gravitational energy as dark energy: Concordance of cosmological tests

abstract:
  We provide preliminary quantitative evidence that a new solution to averaging
the observed inhomogeneous structure of matter in the universe [gr-qc/0702082,
arxiv:0709.0732], may lead to an observationally viable cosmology without
exotic dark energy. We find parameters which simultaneously satisfy three
independent tests: the match to the angular scale of the sound horizon detected
in the cosmic microwave background anisotropy spectrum; the effective comoving
baryon acoustic oscillation scale detected in galaxy clustering statistics; and
type Ia supernova luminosity distances. Independently of the supernova data,
concordance is obtained for a value of the Hubble constant which agrees with
the measurement of the Hubble Key team of Sandage et al [astro-ph/0603647].
Best-fit parameters include a global average Hubble constant H_0 = 61.7
(+1.2/-1.1) km/s/Mpc, a present epoch void volume fraction of f_{v0} = 0.76
(+0.12/-0.09), and an age of the universe of 14.7 (+0.7/-0.5) billion years as
measured by observers in galaxies. The mass ratio of non-baryonic dark matter
to baryonic matter is 3.1 (+2.5/-2.4), computed with a baryon-to-photon ratio
that concords with primordial lithium abundances.


title: Spectral Functions and Nuclear Response

abstract:
  I discuss the relation between the nuclear response and the Green function
describing the propagation of a nucleon in the nuclear medium. Within this
formalism, the widely used expressions in terms of spectral functions can be
derived in a consistent and rigorous fashion. The results of recent
applications to the study of the inclusive electron-nucleus cross section in
the impulse approximation regime are brielfy analyzed.


title: Cosmological Acceleration from Virtual Gravitons

abstract:
  Intrinsic properties of the space itself and quantum fluctuations of its
geometry are sufficient to provide a mechanism for the acceleration of
cosmological expansion (dark energy effect). Applying
Bogoliubov-Born-Green-Kirkwood-Yvon hierarchy approach to self-consistent
equations of one-loop quantum gravity, we found exact solutions that yield
acceleration. The permanent creation and annihilation of virtual gravitons is
not in exact balance because of the expansion of the Universe. The excess
energy comes from the spontaneous process of graviton creation and is trapped
by the background. It provides the macroscopic quantum effect of cosmic
acceleration.


title:
Few layer graphene on SiC, pyrolitic graphite and graphene: a Raman
  scattering study

abstract:
  The results of micro-Raman scattering measurements performed on three
different ``graphitic'' materials: micro-structured disks of highly oriented
pyrolytic graphite, graphene multi-layers thermally decomposed from carbon
terminated surface of 4H-SiC and an exfoliated graphene monolayer are
presented. Despite its multi-layer character, most parts of the surface of the
graphitized SiC substrates shows a single-component, Lorentzian shape, double
resonance Raman feature in striking similarity to the case of a single graphene
monolayer. Our observation suggests a very weak electronic coupling between
graphitic layers on the SiC surface, which therefore can be considered to be
graphene multi-layers with a simple (Dirac-like) band structure.


title: Multi-dimensional Virasoro algebra and quantum gravity

abstract:
  I review the multi-dimensional generalizations of the Virasoro algebra, i.e.
the non-central Lie algebra extensions of the algebra vect(N) of general vector
fields in N dimensions, and its Fock representations. Being the Noether
symmetry of background independent theories such as N-dimensional general
relativity, this algebra is expected to be relevant to the quantization of
gravity. To this end, more complicated modules which depend on dynamics in the
form of Euler-Lagrange equations are described. These modules can apparently
only be interpreted as quantum fields if spacetime has four dimensions and both
bosons and fermions are present.


title:
Manifestly covariant canonical quantization of gravity and
  diffeomorphism anomalies in four dimensions

abstract:
  Canonical quantization of gravity requires knowledge about the representation
theory of its constraint algebra, which is physically equivalent to the algebra
of arbitrary 4-diffeomorphisms. All interesting lowest-energy representations
are projective, making the relevant algebra into a four-dimensional
generalization of the Virasoro algebra. Such diffeomorphism anomalies are
invisible in field theory, because the relevant cocycles are functionals of the
observer's trajectory in spacetime. The multi-dimensional Virasoro algebra acts
naturally in the phase space of arbitrary histories, with dynamics playing the
role of first-class constraints. General relativity is regularized by expanding
all fields in Taylor series around the observer's trajectory, and truncating at
some fixed order. This regularized but manifestly general-covariant theory is
quantized in the history phase space, and dynamics is imposed afterwards, in
analogy with BRST quantization. Infinities arise when the regularization is
removed; it is presently unclear how these should be dealt with.


title: Non-minimally coupled multi-scalar black holes

abstract:
  We study the static, spherically symmetric black hole solutions for a
non-minimally coupled multi-scalar theory. We find numerical solutions for
values of the scalar fields when a certain constraint on the maximal charge is
satisfied. Beyond this constraint no black hole solutions exist. This
constraint therefore corresponds to extremal solutions, however, this does not
match the \kappa = 0 constraint which typically indicates extremal solutions in
other models. This implies that the set of extremal solutions have non-zero,
finite and varying surface gravity. These solutions also violate the no-hair
theorems for N>1 scalar fields and have previously been proven to be linearly
stable.


title: Dissipative Hyperbolic Geometric Flow

abstract:
  In this paper we introduce and study a new kind of hyperbolic geometric flows
--dissipative hyperbolic geometric flow. This kind of flow is defined by a
system of quasilinear wave equations with dissipative terms. Some interesting
exact solutions are given, in particular, a new concept-- hyperbolic Ricci
soliton is introduced and some of its geometric properties are described. We
also establish the short-time existence and uniqueness theorem for the
dissipative hyperbolic geometric flow, and prove the nonlinear stability of the
flow defined on the Euclidean space of dimension larger than 2. Wave character
of the evolving metrics and curvatures is illustrated and the nonlinear wave
equations satisfied by the curvatures are derived.


title:
Calculation of Magnetic Field Noise from High-Permeability Magnetic
  Shields and Conducting Objects with Simple Geometry

abstract:
  High-permeability magnetic shields generate magnetic field noise that can
limit the sensitivity of modern precision measurements. We show that
calculations based on the fluctuation-dissipation theorem allow quantitative
evaluation of magnetic field noise, either from current or magnetization
fluctuations, inside enclosures made of high-permeability materials. Explicit
analytical formulas for the noise are derived for a few axially symmetric
geometries, which are compared with results of numerical finite element
analysis. Comparison is made between noises caused by current and magnetization
fluctuations inside a high-permeability shield and also between
current-fluctuation-induced noises inside magnetic and non-magnetic conducting
shells. A simple model is suggested to predict power-law decay of noise spectra
beyond quasi-static regime. Our results can be used to assess noise from
existing shields and to guide design of new shields for precision measurements.


title: Electroweak Contributions to Squark Pair Production at the LHC

abstract:
  In this paper we compute electroweak contributions to the production of
squark pairs at hadron colliders. These include the exchange of electroweak
gauge bosons in the s-channel as well as electroweak gaugino exchange in the t-
and/or u-channel. In many cases these can interfere with the dominant QCD
contributions. As a result, we find sizable contributions to the production of
two SU(2) doublet squarks. At the LHC, they amount to 10 to 20% for typical
mSUGRA (or CMSSM) scenarios, but in more general scenarios they can vary
between -40 and +55%, depending on size and sign of the SU(2) gaugino mass. The
electroweak contribution to the total squark pair production rate at the LHC is
about 3.5 times smaller.


title: Non-Gaussianity in the modulated reheating scenario

abstract:
  We investigate the non-Gaussianity of primordial curvature perturbation in
the modulated reheating scenario where the primordial perturbation is generated
due to the spacial fluctuation of the inflaton decay rate to radiation. We use
the $\delta N$ formalism to evaluate the trispectrum of curvature perturbation
as well as its bispectrum. We give expressions for three non-linear parameters
$f_{NL}, \tau_{NL}$ and $g_{NL}$ in the modulated reheating scenario. If the
intrinsic non-Gaussianity of scalar field fluctuations and third derivative of
the decay rate with respect to scalar fields are negligibly small, $g_{NL}$ has
at least the same order of magnitude as $f_{NL}$. We also give general
inequality between $f_{NL}$ and $\tau_{NL}$ which is true for other
inflationary scenarios as long as primordial non-Gaussianity comes from
super-horizon evolution.


title: Generalized Fubini instantons

abstract:
  We show that $(1+2)$ nonlinear Klein-Gordon equation with negative coupling
admits an exact solution which appears to be the linear superposition of the
plane wave and the nonsingular rational soliton. We show that the same approach
allows to construct the solution of similar properties for the Euclidean
$\phi^4$ model with broken symmetry. Interestingly, this regular solution will
be of instanton type only in the $D\le 5$ Euclidean space.


title: Prospects for (non-SUSY) new physics with first LHC data

abstract:
  The ATLAS and CMS experiments will take first data soon. I consider here the
prospects for new physics (excluding SUSY) with a few inverse fb of data. This
means processes with signal cross sections of a few 100 fb or less, with clear
and fairly simple signatures - precision comparison of data to Standard Model
tails will take longer, needing more luminosity and very good understanding of
detector calibrations, resolutions and trigger efficiencies. The approach I
take here is signature rather than model based, but examples of models will be
given.


title: Controlling Fano Profiles via Conical Intersections

abstract:
  An ab initio analytical model for Fano resonances in two-channel systems is
presented. We find that the lineshape parameter q factors into a background
contribution q_b that depends only on the uncoupled channels and an interaction
contribution q_i that is affected by the coupling between the channels,
revealing how the overall lineshape parameter q may be controlled. In
particular, we show how conical intersections of the background phase shifts
have an important role in the interplay between q_b and q_i. Finally, control
of Fano transmission profiles through q_b and q_i is demonstrated for quantum
billiards.


title: Evidence of longterm cyclic evolution of radio pulsar periods

abstract:
  The measurements of pulsar frequency second derivatives have shown that they
are 1e2...1e6 times larger than expected for standard pulsar spin-down law.
Moreover, the second derivatives as well as braking indices are even negative
for about half the pulsars. We explain these paradoxical results on the basis
of the statistical analysis of the rotational parameters f0, f1 and f2 of the
subset of 295 pulsars taken mostly from the ATNF database. We have found a
strong correlation between f2 and f1 for both f2 > 0 (correlation coefficient r
~ 0.9) and f2 < 0 (r ~ 0.85), as well as between f0 and f1 (r ~ 0.6...0.7). We
interpret these dependencies as evolutionary ones due to f1 being nearly
proportional to the pulsars' age.
  The derived statistical relations as well as "anomalous" values of f2 are
well described by assuming the existence of long-time variations of the
spin-down rate. The pulsar frequency evolution, therefore, consists of secular
change of f0_{ev}(t), f1_{ev}(t) and f2_{ev}(t) according to the power law with
n ~ 5, the irregularities, observed within the timespan as timing noise, and
the non-monotonous variations on the timescale of several tens of years, which
is larger than that of the timespan. It is possible that the nature of
long-term variations is similar to that of short-term ones. The idea of
non-constant secular pulsars' braking index n is also analysed.


title: The Monoceros very-high-energy gamma-ray source

abstract:
  The H.E.S.S. telescope array has observed the complex Monoceros Loop
SNR/Rosette Nebula region which contains unidentified high energy EGRET sources
and potential very-high-energy (VHE) gamma-ray source. We announce the
discovery of a new point-like VHE gamma-ray sources, HESS J0632+057. It is
located close to the rim of the Monoceros SNR and has no clear counterpart at
other wavelengths. Data from the NANTEN telescope have been used to investigate
hadronic interactions with nearby molecular clouds. We found no evidence for a
clear association. The VHE gamma-ray emission is possibly associated with the
lower energy gamma-ray source 3EG J0634+0521, a weak X-ray source 1RXS
J063258.3+054857 and the Be-star MWC 148.


title:
Counting descent pairs with prescribed colors in the colored permutation
  groups

abstract:
  We define new statistics, (c, d)-descents, on the colored permutation groups
Z_r \wr S_n and compute the distribution of these statistics on the elements in
these groups. We use some combinatorial approaches, recurrences, and generating
functions manipulations to obtain our results.


title:
Observational appearances of isolated stellar-mass black hole accretion
  - theory and observations

abstract:
  General properties of accretion onto isolated stellar mass black holes in the
Galaxy are discussed. An analysis of plasma internal energy growth during the
infall is performed. Adiabatic heating of collisionless accretion flow due to
magnetic adiabatic invariant conservation is 25% more efficient than in the
standard non-magnetized gas case. It is shown that magnetic field line
reconnections in discrete current sheets lead to significant nonthermal
electron component formation, which leads to a formation of a hard (UV, X-ray,
up to gamma), highly variable spectral component in addition to the standard
synchrotron optical component first derived by Shvartsman generated by thermal
electrons in the magnetic field of the accretion flow. Properties of accretion
flow emission variability are discussed. Observation results of two single
black hole candidates - gravitational lens MACHO-1999-BLG-22 and radio-loud
x-ray source with featureless optical spectrum J1942+10 - in optical band with
high temporal resolution are presented and interpreted in the framework of the
proposed model.


title: Chemodynamical evolution of interacting galaxies: the GalMer view

abstract:
  We have undertaken a large set of simulations of galaxy interactions and
mergers (GalMer Project) in order to study the physical processes related to
galaxy encounters. All morphological types along the Hubble sequence are
considered in the initial conditions of the two colliding galaxies, with
varying bulge-to-disk ratios and gas mass fractions. Different types of orbits
are simulated, direct and retrograde, according to the initial relative energy
and impact parameter. The self gravity of stars, gas and dark matter is taken
into account through a tree-code algorithm, the gas hydrodynamics through SPH.
Star formation is included adopting a density-dependent Schmidt law. This wide
library of galaxy interactions and mergers, containing, at present, about 900
simulations of major encounters, represents an unique tool to investigate
statistically the chemodynamical evolution of interacting systems. In the
following, we present and discuss some results obtained exploring the dataset,
together with some future perspectives.


title: New physics in Bs decays to J/psi and phi

abstract:
  This paper is concerned with the physics of meson decays to J/psi and
phi.These decays have been observed at the Tevatron [7] and, in particular,
should be copiously observed at the LHCb detector. This paper gives a concise
presentation of the basic physics analysis and a general formalism for
analyzing the signals of CP violation.


title:
Towards the computation of the convex hull of a configuration from its
  corresponding separating matrix

abstract:
  In this paper, we cope with the following problem: compute the size of the
convex hull of a configuration C, where the given data is the number of
separating lines between any two points of the configuration (where the lines
are generated by pairs of other points of the configuration).
  We give an algorithm for the case that the convex hull is of size 3, and a
partial algorithm and some directions for the case that the convex hull is of
size bigger than 3.


title: SDLS: a Matlab package for solving conic least-squares problems

abstract:
  This document is an introduction to the Matlab package SDLS (Semi-Definite
Least-Squares) for solving least-squares problems over convex symmetric cones.
The package is shortly presented through the addressed problem, a sketch of the
implemented algorithm, the syntax and calling sequences, a simple numerical
example and some more advanced features. The implemented method consists in
solving the dual problem with a quasi-Newton algorithm. We note that SDLS is
not the most competitive implementation of this algorithm: efficient, robust,
commercial implementations are available (contact the authors). Our main goal
with this Matlab SDLS package is to provide a simple, user-friendly software
for solving and experimenting with semidefinite least-squares problems. Up to
our knowledge, no such freeware exists at this date.


title:
Non-relativistic limit in the 2+1 Dirac Oscillator: A Ramsey
  Interferometry Effect

abstract:
  We study the non-relativistic limit of a paradigmatic model in Relativistic
Quantum Mechanics, the two-dimensional Dirac oscillator. Remarkably, we find a
novel kind of Zitterbewegung which persists in this non-relativistic regime,
and leads to an observable deformation of the particle orbit. This effect can
be interpreted in terms of a Ramsey Interferometric phenomenon, allowing an
insightful connection between Relativistic Quantum Mechanics and Quantum
Optics. Furthermore, subsequent corrections to the non-relativistic limit,
which account for the usual spin-orbit Zitterbewegung, can be neatly understood
in terms of a Mach-Zehnder interferometer.


title: Modified Averaging Processes in Cosmology and the Structured FRW model

abstract:
  We study the volume averaging of inhomogeneous metrics within GR and discuss
its shortcomings such as gauge dependence, singular behavior as a result of
caustics, and causality violations. To remedy these shortcomings, we suggest
some modifications to this method. As a case study we focus on the
inhomogeneous structured FRW model based on a flat LTB metric. The effect of
averaging is then studied in terms of an effective backreaction fluid. It is
shown that, contrary to the claims in the literature, the backreaction fluid
behaves like a dark matter component, instead of dark energy, having a density
of the order of 10^{-5} times the matter density, and most importantly, it is
gauge dependent.


title: GloptiPoly 3: moments, optimization and semidefinite programming

abstract:
  We describe a major update of our Matlab freeware GloptiPoly for parsing
generalized problems of moments and solving them numerically with semidefinite
programming.


title: Nature of the spin dynamics and 1/3 magnetization plateau in azurite

abstract:
  We present a specific heat and inelastic neutron scattering study in magnetic
fields up into the 1/3 magnetization plateau phase of the diamond chain
compound azurite Cu$_3$(CO$_3$)$_2$(OH)$_2$. We establish that the
magnetization plateau is a dimer-monomer state, {\it i.e.}, consisting of a
chain of $S = 1/2$ monomers, which are separated by $S = 0$ dimers on the
diamond chain backbone. The effective spin couplings $J_{mono}/k_B = 10.1(2)$ K
and $J_{dimer}/k_B = 1.8(1)$ K are derived from the monomer and dimer
dispersions. They are associated to microscopic couplings $J_1/k_B = 1(2)$ K,
$J_2/k_B = 55(5)$ K and a ferromagnetic $J_3/k_B = -20(5)$ K, possibly as
result of $d_{z^2}$ orbitals in the Cu-O bonds providing the superexchange
pathways.


title: Rings and shells of "dark matter" as MOND artifacts

abstract:
  MOND predicts that a mass, M, contained within its transition radius
r_t=(MG/a0)^{1/2}, may exhibit a feature at about that radius in the form of a
shell, or projected ring, in the deduced distribution of its phantom dark
matter. This occurs despite the absence of any underlying feature in the true
(``baryon'') source distribution itself. The phenomenon is similar to the
appearance of an event horizon and other unusual physics ``in the middle of
nothing'' near the transition radius of General Relativity $MG/c^2$. We
consider the possibility that this pure MOND phenomenon is in the basis of the
recent finding of such a ring in the galaxy cluster Cl 0024+17 by Jee et al. We
find that the parameters of the observed ring can be naturally explained in
this way; this feature may therefore turn out to be a direct evidence for MOND.
We study this phenomenon in simple, axisymmetric configurations aligned with
the line of sight: spherical masses, a dumbbell of spherical masses, and an
elongated, thin structure. The properties of the apparent ring: its radius,
surface density, and contrast, depend on the form of the MOND interpolating
function and on the exact three dimensional distribution of the sources (the
thin-lens approximation is quite invalid in MOND). We also comment on the
possible appearance of orphan features, marking the Newtonian-to-MOND
transition, in high surface brightness galaxies. In particular, we find that
previously unexplained structure in the rotation curves of some galaxies may be
evidence for such features.


title: When are recommender systems useful?

abstract:
  Recommender systems are crucial tools to overcome the information overload
brought about by the Internet. Rigorous tests are needed to establish to what
extent sophisticated methods can improve the quality of the predictions. Here
we analyse a refined correlation-based collaborative filtering algorithm and
compare it with a novel spectral method for recommending. We test them on two
databases that bear different statistical properties (MovieLens and Jester)
without filtering out the less active users and ordering the opinions in time,
whenever possible. We find that, when the distribution of user-user
correlations is narrow, simple averages work nearly as well as advanced
methods. Recommender systems can, on the other hand, exploit a great deal of
additional information in systems where external influence is negligible and
peoples' tastes emerge entirely. These findings are validated by simulations
with artificially generated data.

categories: cs.IR cs.CY cs.DL cs.DS physics.data-an physics.soc-ph


title:
Nulling interferometry: performance comparison between Antarctica and
  other ground-based sites

abstract:
  Detecting the presence of circumstellar dust around nearby solar-type main
sequence stars is an important pre-requisite for the design of future
life-finding space missions such as ESA's Darwin or NASA's Terrestrial Planet
Finder (TPF). The high Antarctic plateau may provide appropriate conditions to
perform such a survey from the ground. We investigate the performance of a
nulling interferometer optimised for the detection of exozodiacal discs at Dome
C, on the high Antarctic plateau, and compare it to the expected performance of
similar instruments at temperate sites. Based on the currently available
measurements of the turbulence characteristics at Dome C, we adapt the GENIEsim
software (Absil et al. 2006, A&A 448) to simulate the performance of a nulling
interferometer on the high Antarctic plateau. To feed a realistic instrumental
configuration into the simulator, we propose a conceptual design for ALADDIN,
the Antarctic L-band Astrophysics Discovery Demonstrator for Interferometric
Nulling. We assume that this instrument can be placed above the 30-m high
boundary layer, where most of the atmospheric turbulence originates. We show
that an optimised nulling interferometer operating on a pair of 1-m class
telescopes located 30 m above the ground could achieve a better sensitivity
than a similar instrument working with two 8-m class telescopes at a temperate
site such as Cerro Paranal. The detection of circumstellar discs about 20 times
as dense as our local zodiacal cloud seems within reach for typical Darwin/TPF
targets in a integration time of a few hours. Moreover, the exceptional
turbulence conditions significantly relax the requirements on real-time control
loops, which has favourable consequences on the feasibility of the nulling
instrument.


title: Finite rank approximations of expanding maps with neutral singularities

abstract:
  For a class of expanding maps with neutral singularities we prove the
validity of a finite rank approximation scheme for the analysis of
Sinai-Ruelle-Bowen measures. Earlier results of this sort were known only in
the case of hyperbolic systems.


title: Observation of e+e- to K+K-J/psi via Initial State Radiation at Belle

abstract:
  The process e+e- to K+K-J/psi is observed for the first time via initial
state radiation. The cross section of e+e- to K+K-J/psi for center-of-mass
energies between threshold and 6.0 GeV is measured using 673 fb^{-1} of data
collected with the Belle detector on and off the Upsilon(4S) resonance. We also
find evidence for e+e- to K_S K_S J/psi in the same energy region.


title: Raman Fingerprint of Charged Impurities in Graphene

abstract:
  We report strong variations in the Raman spectra for different single-layer
graphene samples obtained by micromechanical cleavage, which reveals the
presence of excess charges, even in the absence of intentional doping. Doping
concentrations up to ~10^13 cm-2 are estimated from the G peak shift and width,
and the variation of both position and relative intensity of the second order
2D peak. Asymmetric G peaks indicate charge inhomogeneity on the scale of less
than 1 micron.


title: Transition Distribution Amplitudes

abstract:
  We give a brief overview of the theoretical status of the Transition
Distribution Amplitudes and discuss their experimental near future.


title: Host galaxies of bright high redshift quasars: Luminosities and colours

abstract:
  We present the results of a near-infrared imaging study of high redshift
(z~3) quasars using the ESO-VLT. Our targets were selected to have luminosities
among the highest known (absolute magnitude M_B <~ -28. We searched for
resolved structures underlying the bright point-source nuclei by comparing the
QSO images with stars located in the same fields. Two QSOs (HE2348-1444 at
z=2.904 and HE2355-5457 at z=2.933) are clearly resolved in K_S, and with
somewhat lower significance also in H; one object is resolved only in K_S. At
these redshifts, H and K_S correspond almost exactlly to rest-frame B and V,
respectively, with virtually no K-correction. We also report briefly the
non-detection of some additional QSOs. The detected host galaxies are extremely
luminous with M_V ~ -25. Their rest-frame B-V colours, however, are close to
zero in the Vega system, indicating substantial contributions from young stars
and a stellar mass-to-light ratio below 1 (in solar units). Tentatively
converting M_V and B-V into rough estimates of stellar masses, we obtain values
of M_star in the range of several 10^11 M_sun, placing them within the
high-mass range of recent high-redshift galaxy surveys. We present optical
spectra and use CIV line width measurements to predict virial black hole
masses, obtaining typical values of M_bh ~ 5x10^9 M_sun. With respect to the
known correlation between host galaxy luminosity L_V(host) and M_bh, our
measurements reach to higher luminosities and redshifts than previous studies,
but are completely consistent with them. Comparing our objects with the local
(z~0) M_bh - M_bulge relation and taking also the low stellar mass-to-light
ratios into account, we find tentative evidence for an excess in the
M_bh/M_bulge mass ratio at z~3.


title:
Comment on "Dynamics of nuclear fluid. VIII. Time-dependent Hartree-Fock
  approximation from a classical point of view"

abstract:
  The phase-space paths introduced by Cheuk-Yin Wong in Phys. Rev.C25, 1460
(1982) and discussed recently in the literature can be used for calculation of
evolution of the Wigner function to first order in the time increments only.
The first-order solutions are helpful to determine the phase-space Green
function in the framework of the phase-space path integral method.


title: Multiwavelength Gamma-Ray Bursts Observations with ECLAIRs

abstract:
  ECLAIRs is the next space borne instrument that will be fully dedicated to
multi-wavelength studies of Gamma-Ray Bursts (GRBs). It consists of a coded
mask telescope with a wide (~2 sr) field of view, made of 6400 CdTe pixels
(~1000 cm^2), which will work in the 4-300 keV energy band. It is expected to
localise ~80 GRBs/yr, thanks to the on-board real time event processing. The
GRBs (and other transients) coordinates will be distributed within a few
seconds from the onset of the burst with a typical uncertainty of ~5-10 arcmin.
The detection system will also include a soft X-ray camera (1-10 keV) allowing
to study in detail the prompt soft X-ray emission and to reduce the error box
for about half of the GRBs seen by ECLAIRs to ~30 arcsec. ECLAIRs is expected
to be flown in late 2011 and to be the only instrument capable of providing GRB
triggers with sufficient localisation accuracy for GRB follow-up observations
with the powerful ground based spectroscopic telescopes available by then. We
will present the current status of the ECLAIRs project and its possible
developments.


title:
Random walk of magnetic field lines for different values of the
  energy-range spectral index

abstract:
  An analytical nonlinear description of field-line wandering in partially
statistically magnetic systems was proposed recently [A. Shalchi, I. Kourakis,
Astronomy and Astrophysics, 470, 405 (2007)]. In this article we investigate
the influence of the wave-spectrum in the energy-range onto field line random
walk by applying this formulation. It is demonstrated that in all considered
cases we clearly obtain a superdiffusive behaviour of the field-lines. If the
energy-range spectral index exceeds unity a free-streaming behaviour of the
field-lines can be found for all relevant length-scales of turbulence. Since
the superdiffusive results obtained for the slab model are exact, it seems that
superdiffusion is the normal behavior of field line wandering.


title:
The harmonic oscillator on Riemannian and Lorentzian configuration
  spaces of constant curvature

abstract:
  The harmonic oscillator as a distinguished dynamical system can be defined
not only on the Euclidean plane but also on the sphere and on the hyperbolic
plane, and more generally on any configuration space with constant curvature
and with a metric of any signature, either Riemannian (definite positive) or
Lorentzian (indefinite). In this paper we study the main properties of these
`curved' harmonic oscillators simultaneously on any such configuration space,
using a Cayley-Klein (CK) type approach, with two free parameters $\ki, \kii$
which altogether correspond to the possible values for curvature and signature
type: the generic Riemannian and Lorentzian spaces of constant curvature
(sphere ${\bf S}^2$, hyperbolic plane ${\bf H}^2$, AntiDeSitter sphere ${\bf
AdS}^{\unomasuno}$ and DeSitter sphere ${\bf dS}^{\unomasuno}$) appear in this
family, with the Euclidean and Minkowski spaces as flat limits.
  We solve the equations of motion for the `curved' harmonic oscillator and
obtain explicit expressions for the orbits by using three different methods:
first by direct integration, second by obtaining the general CK version of the
Binet's equation and third, as a consequence of its superintegrable character.
The orbits are conics with centre at the potential origin in any CK space,
thereby extending this well known Euclidean property to any constant curvature
configuration space. The final part of the article, that has a more geometric
character, presents those results of the theory of conics on spaces of constant
curvature which are pertinent.


title:
Band gap unification of partially Si-substituted single wall carbon
  nanotubes

abstract:
  The atomic and electronic structure of a set of pristine single wall SiC
nanotubes as well as Si-substituted carbon nanotubes and a SiC sheet was
studied by the LDA plane wave band structure calculations. Consecutive
substitution of carbon atoms by Si leads to a gap opening in the energetic
spectrum of the metallic (8,8) SWCNT with approximately quadratic dependence of
the band gap upon the Si concentration. The same substitution for the
semiconductor (10,0) SWCNT results in a band gap minimum (0.27 eV) at ~25% of
Si concentration. In the Si concentration region of 12-18%, both types of
nanotubes have less than 0.5 eV direct band gaps at the Gamma-Gamma point. The
calculation of the chiral (8,2) SWSi_0.15C_0.85NT system gives a similar (0.6
eV) direct band gap. The regular distribution of Si atoms in the atomic lattice
is by ~0.1 eV/atom energetically preferable in comparison with a random
distribution. Time dependent DFT calculations showed that the silicon
substitution sufficiently increases (roughly by one order of magnitude) the
total probability of optical transitions in the near infrared region, which is
caused by the opening of the direct band gap in metallic SWCNTs, the
unification of the nature and energy of band gaps of all SWCNT species, the
large values of <Si3p|r|Si3s> radial integrals and participation of Si3d states
in chemical bonding in both valence and conductance bands.


title:
Search for very high energy gamma rays from possible ultra-high energy
  cosmic ray sources by the MAGIC Telescope

abstract:
  The origin of ultra-high energy (UHE) cosmic rays is still an open question.
In the present work, we searched the possible UHE cosmic ray sources using the
MAGIC telescope for the associated very high energy (VHE) gamma ray emission.
Due to constrained propagation distance of such cosmic rays, we selected nearby
galaxies in vicinity of the direction of the AGASA triplet and a HiRes UHE
cosmic ray event: NGC 3610 and NGC 3613 (quasar remnants); Arp 299 (a system of
colliding galaxies). No significant excess in the VHE region was found found
from these objects or their surrounding region. At multi-100 GeV regime, the
upper limits on fluxes were given against gamma ray sources in surrounding
region. The presented limits constrain the flux of a new hypothetical source in
the region, provided the cosmic rays are emitted from a single point-like
origin.


title: Realization of a semiconductor-based cavity soliton laser

abstract:
  The realization of a cavity soliton laser using a vertical-cavity
surface-emitting semiconductor gain structure coupled to an external cavity
with a frequency-selective element is reported. All-optical control of bistable
solitonic emission states representing small microlasers is demonstrated by
injection of an external beam. The control scheme is phase-insensitive and
hence expected to be robust for all-optical processing applications. The
motility of these structures is also demonstrated.


title: A Better Definition of the Kilogram

abstract:
  Fixing the value of Avogadro's constant, the number of atoms in 12 grams of
carbon-12, at exactly 84446886^3 would imply that one gram is the mass of
exactly 18x14074481^3 carbon-12 atoms. This new definition of the gram, and
thereby also the kilogram, is precise, elegant and unchanging in time, unlike
the current 118-year-old artifact kilogram in Paris and the proposed
experimental definitions of the kilogram using man-made silicon spheres or the
watt balance apparatus.


title: Local holomorphic Euler characteristic and instanton decay

abstract:
  We study the local holomorphic Euler characteristic $\chi(x,\mathcal{F})$ of
sheaves near a surface singularity obtained from contracting a line $\ell$
inside a smooth surface $Z$. We prove non-existence of sheaves with certain
prescribed numerical invariants. Non-existence of instantons on $Z$ with
certain charges follows, and we conclude that $\ell^2$ poses an obstruction to
instanton decay. A Macaulay 2 algorithm to compute $\chi$ is made available at
http://www.maths.ed.ac.uk/~s0571100/Instanton/


title: Testing Error Correcting Codes by Multicanonical Sampling of Rare Events

abstract:
  The idea of rare event sampling is applied to the estimation of the
performance of error-correcting codes. The essence of the idea is importance
sampling of the pattern of noises in the channel by Multicanonical Monte Carlo,
which enables efficient estimation of tails of the distribution of bit error
rate. The idea is successfully tested with a convolutional code.


title:
Some fundamental problems for an energy conserving adaptive resolution
  molecular dynamics scheme

abstract:
  Adaptive resolution molecular dynamics (MD) schemes allow for changing the
number of degrees of freedom on the fly and preserve the free exchange of
particles between regions of different resolution. There are two main
alternatives on how to design the algorithm to switch resolution using
auxiliary ''switching'' functions; force based and potential energy based
approach. In this work we show that, in the framework of classical MD, the
latter presents fundamental conceptual problems which make unlikely, if not
impossible, the derivation of a robust algorithm based on the potential energy.


title: Pulse variation of the optical emission of Crab pulsar

abstract:
  The stability of the optical pulse of the Crab pulsar is analyzed based on
the 1 $\mu$s resolution observations with the Russian 6-meter and William
Hershel telescopes equipped with different photon-counting detectors. The
search for the variations of the pulse shape along with its arrival time
stability is performed. Upper limits on the possible short time scale free
precession of the pulsar are placed. The evidence of pulse time of arrival
(TOA) variations on 1.5-2 hours time scale is presented, along with evidence of
small light curve (shape and separation of main and secondary peaks) changes
between data sets, on time scale of years. Also, the fine structure of the main
pulse is studied.


title:
X-Ray Analysis of Oxygen-induced Perpendicular Magnetic Anisotropy in
  Pt/Co/AlOx trilayer

abstract:
  X-ray spectroscopy measurements have been performed on a series of Pt/Co/AlOx
trilayers to investigate the role of Co oxidation in the perpendicular magnetic
anisotropy of the Co/AlOx interface. It is observed that high temperature
annealing modifies the magnetic properties of the Co layer, inducing an
enhancement of the perpendicular magnetic anisotropy. The microscopic
structural properties are analyzed via X-ray Absorption Spectroscopy, X-ray
Magnetic Circular Dichroism and X-ray Photoelectron Spectroscopy measurements.
It is shown that annealing enhances the amount of interfacial oxide, which may
be at the origin of a strong perpendicular magnetic anisotropy.


title: Intrinsic dissipation in cantilevers

abstract:
  We consider the effects of a velocity-independent friction force on
cantilever damping. It is shown that this dissipation mechanism causes
nonlinear effects in the cantilever vibrations. The size of the nonlinearity
increases with decreasing cantilever velocity. Our analysis makes it possible
to understand experiments [Stipe et al, PRL 87, 096801 (2001)] where an
amplitude dependence of the cantilever eigenfrequency and anomalous dissipation
was observed only at small amplitudes.


title:
Test of unparticle long range forces from perihelion precession of
  Mercury

abstract:
  Unparticle exchange gives rise to long range forces which deviate from the
inverse square law due to non-canonical dimension of unparticles. It is well
known that a potential of the form $r^{-n}$ where $n$ is not equal to one gives
rise to a precession in the perihelion of planetary orbits. We calculate the
constraints on unparticle couplings with baryons and leptons from the
observations of perihelion advance of Mercury orbit.


title:
Sur la cohomologie \`a support des fibr\'es en droites sur les
  vari\'et\'es sym\'etriques compl\`etes

abstract:
  Let $X$ be a complete symmetric variety i.e. the wonderful compactification
of a symmetric $G-$homogeneous space (where $G$ is a simply-connected
semi-simple linear algebraic group). If $L$ is a line bundle over $X$ and if
$C$ is a Bialynicki-Birula cell of codimension $c$ in $X$, then the Lie algebra
$\mathfrak g$ of $G$ operates naturally on the cohomology group with support :
$H^c_C(L)$. One gives here a necessary condition on the cell $C$ for that
$\mathfrak g-$module have a finite dimensional simple subquotient. As
applications one calculates the Euler-Poincar\'e characteristic of $L$ over $X$
and one estimates the higher cohomology group $H^d(X,L)$, $d \ge 0$, with exact
formulae in some cases among which the case of the complete conic variety. --
\'Etant donn\'e un groupe alg\'ebrique lin\'eaire semi-simple G, on
s'int\'eresse aux compactifications magnifiques des G?espaces homog\`enes
sym\'etriques. Si X est une telle compactification, si L est un fibr\'e en
droites G?lin\'earis\'e sur X et si C est une cellule de Bialynicki-Birula de X
de codimension c, alors l'alg\`ebre de Lie g de G op\`ere naturellement sur le
groupe de cohomologie \`a support Hc C (L). On donne ici une condition
n\'ecessaire, portant sur la cellule C, pour que ce g?module poss\`ede un
sous-quotient simple de dimension finie. On en d\'eduit une formule pour la
caract\'eristique d'Euler-Poincar\'e de L sur X et une estimation (exacte pour
certains cas dont celui de la vari\'et\'e des coniques compl\`etes) des groupes
de cohomologie sup\'erieure Hd(X,L), d ? 0.


title:
Stimulated Globular Scattering of Laser Radiation in Photonic Crystals:
  Temperature Dependences

abstract:
  Stimulated globular scattering (SGS) characteristics (frequency shifts,
threshold, conversion efficiency) have been studied in photonic crystals
(synthetic opal matrices and opal nanocomposites) at different temperatures.
Results have been compared with stimulated Raman scattering investigations in
calcite single crystals. In both cases temperature lowering from +20 C to -196
C resulted in the stimulated scattering energy increase and its redistribution
to the higher order components.


title:
Generalized characteristics of the homogenous magneto hydrodynamical
  equations

abstract:
  With the help of the generalized characteristics(GC) of the first order
partial differential equations(PDE) we calculate the differential equation
system of characteristics of the homogenous magneto hydrodynamical
equations(MHD).


title: The isodiametric problem with lattice-point constraints

abstract:
  In this paper, the isodiametric problem for centrally symmetric convex bodies
in the Euclidean d-space R^d containing no interior non-zero point of a lattice
L is studied. It is shown that the intersection of a suitable ball with the
Dirichlet-Voronoi cell of 2L is extremal, i.e., it has minimum diameter among
all bodies with the same volume. It is conjectured that these sets are the only
extremal bodies, which is proved for all three dimensional and several
prominent lattices.


title: Beam Wandering in the Atmosphere: The Effect of Partial Coherence

abstract:
  The effect of a random phase screen on laser beam wander in a turbulent
atmosphere is studied theoretically. The method of photon distribution function
is used to describe the photon kinetics of both weak and strong turbulence. By
bringing together analytical and numerical calculations, we have obtained the
variance of beam centroid deflections caused by scattering on turbulent eddies.
It is shown that an artificial distortion of the initial coherence of the
radiation can be used to decrease the wandering effect. The physical mechanism
responsible for this reduction and applicability of our approach are discussed.


title:
A post-Newtonian diagnosis of quasiequilibrium configurations of neutron
  star-neutron star and neutron star-black hole binaries

abstract:
  We use a post-Newtonian diagnostic tool to examine numerically generated
quasiequilibrium initial data sets for non-spinning double neutron star and
neutron star-black hole binary systems. The PN equations include the effects of
tidal interactions, parametrized by the compactness of the neutron stars and by
suitable values of ``apsidal'' constants, which measure the degree of
distortion of stars subjected to tidal forces. We find that the post-Newtonian
diagnostic agrees well with the double neutron star initial data, typically to
better than half a percent except where tidal distortions are becoming extreme.
We show that the differences could be interpreted as representing small
residual eccentricity in the initial orbits. In comparing the diagnostic with
preliminary numerical data on neutron star-black hole binaries, we find less
agreement.


title: The Riemann Zeta-Function and Hecke Congruence Subgroups. II

abstract:
  This is a rework of our old file, which has been left unpublished since
September 1994, on an explicit spectral decomposition of the fourth power
moment of the Riemann zeta-function against a weight which is the square of a
Dirichlet polynomial. At this occasion we add an explicit treatment of
generalized Kloosterman sums associated with arbitrary Hecke congruence
subgroups (Section 15), which might have an independent interest. At the end
(Section 36) of our discussion, we set out a few problems on the distribution
of eigenvalues of the hyperbolic Laplacian, which appear to us to be related to
the nature of the sixth power moment of the Riemann zeta-function. The contents
of this work were presented in a worshop at RIMS Kyoto University on October
18, 2007.
  In this second version, some corrections are made in the part on generalized
Kloosterman sums, and in Addendum a mention is made concerning a recent work by
C.P. Hughes and M.P. Young (0709.2345).


title:
Charged lepton distributions as a probe of contact e+e-HZ interactions
  at a linear collider with polarized beams

abstract:
  We examine very general four-point interactions arising from new physics and
contributing to the Higgs production process e+e- -> HZ. We write all possible
forms for these interactions consistent with Lorentz invariance. We allow the
possibility of CP violation. Contributions to the process from anomalous ZZH
and gamma ZH interactions studied earlier arise as a special case of our
four-point amplitude. We consider the decay of Z into a charged lepton pair and
obtain expressions for angular distributions of charged leptons arising from
the interference of the four-point contribution with the standard-model
contribution. We take into account possible longitudinal or transverse beam
polarization likely to be available at a linear collider. We examine several
correlations which can be used to study the various form factors present in the
e+e-HZ contact interactions. We also obtain the sensitivity of these
correlations in constraining the new-physics interactions at a linear collider
operating at a centre-of-mass energy of 500 GeV with longitudinal or transverse
polarization.


title: Seshadri fibrations of algebraic surfaces

abstract:
  We refine results of Hwang, Keum and Szemberg, Tutaj-Gasinska which relate
local invariants - Seshadri constants - of ample line bundles on surfaces to
the global geometry - fibration structure. We show that the same picture
emerges when looking at Seshadri constants measured at any finite subset of the
given surface.


title: Symmetric identities on Bernoulli polynomials

abstract:
  In this paper, we obtain a generalization of an identity due to Carlitz on
Bernoulli polynomials. Then we use this generalized formula to derive two
symmetric identities which reduce to some known identities on Bernoulli
polynomials and Bernoulli numbers, including the Miki identity.


title:
Possible crossover from BCS superconductivity to Bose-Einstein
  condensate in quark matter

abstract:
  The possibility of the crossover from the BCS pairing to the Bose-Einstein
condensate (BEC) of diquarks with going down in density is discussed in the
framework of in the Nambu Jona-Lasinio (NJL) model. We find that the quark
matter at moderate density may be close to the intermediate of the crossover,
the precursory regime to the BEC phase.


title: H-atom bombardment of CO2, HCOOH and CH3CHO containing ices

abstract:
  Context: Hydrogenation reactions are expected to be among the most important
surface reactions on interstellar ices. However, solid state astrochemical
laboratory data on reactions of H-atoms with common interstellar ice
constituents are largely lacking. Aims: The goal of our laboratory work is to
determine whether and how carbon dioxide (CO2), formic acid (HCOOH) and
acetaldehyde (CH3CHO) react with H-atoms in the solid state at low temperatures
and to derive reaction rates and production yields. Methods: Pure CO2, HCOOH
and CH3CHO interstellar ice analogues are bombarded by H-atoms in an ultra-high
vacuum experiment. The ices are monitored by reflection absorption infrared
spectroscopy and the reaction products are detected in the gas phase through
temperature programmed desorption to determine the destruction and formation
yields as well as the corresponding reaction rates. Results: Within the
sensitivity of our set-up we conclude that H-atom bombardment of pure CO2 and
HCOOH ice does not result in detectable reaction products. The upper limits on
the reaction rates are less or equal to 7e(-17) cm^2/s which make it unlikely
that these species play a major role in the formation of more complex organics
in interstellar ices due to reactions with H-atoms. In contrast, CH3CHO does
react with H-atoms. At most 20% is hydrogenated to ethanol (C2H5OH) and a
second reaction route leads to the break-up of the C-C bond to form solid state
CH4 (~20%) as well as H2CO and CH3OH (15-50%). The methane production yield is
expected to be equal to the summed yield of H2CO and CH3OH and therefore CH4
most likely evaporates partly after formation due to the high exothermicity of
the reaction. The reaction rates for CH3CHO destruction depend on ice
temperature and not on ice thickness.


title: Chiral symmetry, Confinement and Nuclear Matter properties

abstract:
  We discuss the possible influence of fundamental QCD properties such as
spontaneous chiral symmetry breaking and nucleon substructure on nuclear matter
properties. We propose a chiral version of the relativistic $\sigma-\omega$
model in which the attractive background scalar field is associated with the
chiral invariant field governing the radial fluctuations of the quark
condensate. Nuclear matter stability is ensured once the scalar response of the
nucleon depending on the quark confinement mechanism is properly incorporated.
The needed parameters are estimated from lattice results and a satisfactory
description of bulk properties follows, the only really free parameter being
the $\omega NN$ coupling constant. Pion loops can be also incorporated to
obtain in a consistent way the finite density chiral susceptibilities. A good
description of the asymmetry energy is obtained once the full rho meson
exchange and Fock terms are included.


title: Quantitative recurrence in two-dimensional extended processes

abstract:
  Under some mild condition, a random walk in the plane is recurrent. In
particular each trajectory is dense, and a natural question is how much time
one needs to approach a given small neighborhood of the origin. We address this
question in the case of some extended dynamical systems similar to planar
random walks, including $\ZZ^2$-extension of hyperbolic dynamics. We define a
pointwise recurrence rate and relate it to the dimension of the process, and
establish a convergence in distribution of the rescaled return times near the
origin.


title: On the 3/4-Conjecture for Fix-Free Codes -- A Survey

abstract:
  In this survey we concern ourself with the question, wether there exists a
fix-free code for a given sequence of codeword lengths. For a given alphabet,
we obtain the {\em Kraftsum} of a code, if we divide for every length the
number of codewords of this length in the code by the total number of all
possible words of this length and then take summation over all codeword lengths
which appears in the code. The same way the Kraftsum of a lengths sequence
$(l_1,..., l_n) $ is given by $\sum_{i=1}^n q^{-l_i} $, where $q$ is the
numbers of letters in the alphabet. Kraft and McMillan have shown in
\cite{kraft} (1956), that there exists a prefix-free code with codeword lengths
of a certain lengths sequence, if the Kraftsum of the lengths sequence is
smaller than or equal to one. Furthermore they have shown, that the converse
also holds for all (uniquely decipherable) codes.\footnote{In this survey a
code means a set of words, such that any message which is encoded with these
words can be uniquely decoded. Therefore we omit in future the "uniquely
decipherable" and write only "code".} The question rises, if Kraft's and
McMillan's result can be generalized to other types of codes? Throughout, we
try to give an answer on this question for the class of fix-free codes. Since
any code has Kraftsum smaller than or equal to one, this answers the question
for the second implication of Kraft-McMillan's theorem. Therefore we pay
attention mainly to the first implication.


title: Rapidity Variation of Thermal Parameters at SPS and RHIC

abstract:
  The rapidity dependence of the chemical freeze-out thermal parameters $T$ and
$\mu_B$ are determined at the highest RHIC and SPS energies.
  These show a systematic behavior towards an increase in $\mu_B$ away from
mid-rapidity and a corresponding decrease in the temperature $T$.


title:
On uniform convergence in ergodic theorems for a class of skew product
  transformations

abstract:
  Consider a class of skew product transformations consisting of an ergodic or
a periodic transformation on a probability space (M, B, m) in the base and a
semigroup of transformations on another probability space (W,F,P) in the fibre.
Under suitable mixing conditions for the fibre transformation, we show that the
properties ergodicity, weakly mixing, and strongly mixing are passed on from
the base transformation to the skew product (with respect to the product
measure). We derive ergodic theorems with respect to the skew product on the
product space. The main aim of this paper is to establish uniform convergence
with respect to the base variable for the series of ergodic averages of a
function F on the product of the two probability spaces along the orbits of
such a skew product. Assuming a certain growth condition for the coupling
function, a strong mixing condition on the fibre transformation, and continuity
andintegrability conditions for F, we prove uniform convergence in the base and
L^p(P)-convergence in the fibre. Under an equicontinuity assumption on F we
further show P-almost sure convergence in the fibre. Our work has an
application in information theory: It implies convergence of the averages of
functions on random fields restricted to parts of stair climbing patterns
defined by a direction.


title: Star formation in M33: Spitzer photometry of discrete sources

abstract:
  Combining the relative vicinity of the Local Group spiral galaxy M33 with the
Spitzer images, we investigate the properties of infrared (IR) emission sites
and assess the reliability of the IR emission as a star formation tracer. The
mid- and far-IR emission of M33 was obtained from IRAC and MIPS images from the
Spitzer archive. We compared the photometric results for several samples of
three known types of discrete sources (HII regions, supernovae remnants and
planetary nebulae) with theoretical diagnostic diagrams, and derived the
spectral energy distribution (from 3.6 to 24 micron) of each type of object.
Moreover, we generated a catalogue of 24 micron sources and inferred their
nature from the observed and theoretical colours of the known type sources. We
estimated the star formation rate in M33 both globally and locally, from the IR
emission and from the Halpha emission line. The colours of the typical IR
emissions of HII regions, supernovae remnants and planetary nebulae are
continuous among the different samples, with overlapping regions in the
diagnostic diagrams. The comparison between the model results and the colours
of HII regions indicates a dusty envelope at relatively high temperatures ~600
K, and moderate extinction Av < 10. The 24 micron sources IR colours follow the
regions observationally defined by the three classes of known objects but the
majority of them represent HII regions. The derived total IR luminosity
function is in fact very similar to the HII luminosity function observed in the
Milky Way and in other late type spirals. Even though our completeness limit is
5x10^37 ergs s-1, in low density regions we are able to detect sources five
times fainter than this, corresponding to the faintest possible HII region.
[abridged]


title: Forecasting Seismic Signatures of Stellar Magnetic Activity

abstract:
  For the Sun, a tight correlation between various activity measures and
oscillation frequencies is well documented. For other stars, we have abundant
data on magnetic activity and its changes but not yet on its seismic signature.
A prediction of the activity induced frequency changes in stars based on
scaling the solar relations is presented. This seismic signature of the
activity should be measurable in the data expected within few years.


title:
Existence et equidistribution des matrices de denominateur n dans les
  groupes unitaires et orthogonaux

abstract:
  We study some subsets of rational points in an algebraic groups defined by
open conditions on their projection in the finite adeles points. Using adelic
mixing we are able to prove an equidistribution's result for the projection of
these sets in the real points. As an application, we study the existence and
the repartition of rational unitary matrices having a given denominator. We
prove a local-global principle for this problem and the equirepartition of the
sets of denominator n-matrices when they are not empty. Then we study the more
complicated case of non simply-connected groups applying it to quadratic forms.


title:
Near-infrared spectroscopy of the very low mass companion to the hot DA
  white dwarf PG1234+482

abstract:
  We present a near-infrared spectrum of the hot ($T_{\rm eff}$ $\approx$
55,000 K) DA white dwarf PG 1234+482. We confirm that a very low mass companion
is responsible for the previously recognised infrared photometric excess. We
compare spectra of M and L dwarfs, combined with an appropriate white dwarf
model, to the data to constrain the spectral type of the secondary. We find
that uncertainties in the 2MASS $HK$ photometry of the white dwarf prevent us
from distinguishing whether the secondary is stellar or substellar, and assign
a spectral type of L0$\pm$1 (M9-L1).Therefore, this is the hottest and youngest
($\approx 10^6$ yr) DA white dwarf with a possible brown dwarf companion.


title: Status of the second phase of the MAGIC telescope

abstract:
  The MAGIC 17m diameter Cherenkov telescope will be upgraded with a second
telescope with advanced photon detectors and ultra fast readout within the year
2007. The sensitivity of MAGIC-II, the two telescope system, will be improved
by a factor of 2. In addition the energy threshold will be reduced and the
energy and angular resolution will be improved. The design, status and expected
performance of MAGIC-II is presented here.


title: $\ell^1$ penalty for ill-posed inverse problems

abstract:
  We tackle the problem of recovering an unknown signal observed in an
ill-posed inverse problem framework. More precisely, we study a procedure
commonly used in numerical analysis or image deblurring: minimizing an
empirical loss function balanced by an $l^1$ penalty, acting as a sparsity
constraint. We prove that, by choosing a proper loss function, this estimation
technique enables to build an adaptive estimator, in the sense that it
converges at the optimal rate of convergence without prior knowledge of the
regularity of the true solution


title: Curvature explosion in quotients and applications

abstract:
  We prove that the quotient space of a variationally complete group action is
a good Riemannian orbifold. The result is generalized to singular Riemannian
foliations without horizontal conjugate points.


title: On the topology of minimal orbits in complex flag manifolds

abstract:
  We compute the Euler-Poincar\'e characteristic of the homogeneous compact
manifolds that can be described as minimal orbits for the action of a real form
in a complex flag manifold.


title:
Unifying thermodynamic and kinetic descriptions of single-molecule
  processes: RNA unfolding under tension

abstract:
  We use mesoscopic non-equilibrium thermodynamics theory to describe RNA
unfolding under tension. The theory introduces reaction coordinates,
characterizing a continuum of states for each bond in the molecule. The
unfolding considered is so slow that one can assume local equilibrium in the
space of the reaction coordinates. In the quasi-stationary limit of high
sequential barriers, our theory yields the master equation of a recently
proposed sequential-step model. Non-linear switching kinetics is found between
open and closed states. Our theory unifies the thermodynamic and kinetic
descriptions and offers a systematic procedure to characterize the dynamics of
the unfolding process


title: Swinging and tumbling of elastic capsules in shear flow

abstract:
  The deformation of an elastic micro-capsule in an infinite shear flow is
studied numerically using a spectral method. The shape of the capsule and the
hydrodynamic flow field are expanded into smooth basis functions. Analytic
expressions for the derivative of the basis functions permit the evaluation of
elastic and hydrodynamic stresses and bending forces at specified grid points
in the membrane. Compared to methods employing a triangulation scheme, this
method has the advantage that the resulting capsule shapes are automatically
smooth, and few modes are needed to describe the deformation accurately.
Computations are performed for capsules both with spherical and ellipsoidal
unstressed reference shape. Results for small deformations of initially
spherical capsules coincide with analytic predictions. For initially
ellipsoidal capsules, recent approximative theories predict stable oscillations
of the tank-treading inclination angle, and a transition to tumbling at low
shear rate. Both phenomena have also been observed experimentally. Using our
numerical approach we could reproduce both the oscillations and the transition
to tumbling. The full phase diagram for varying shear rate and viscosity ratio
is explored. While the numerically obtained phase diagram qualitatively agrees
with the theory, intermittent behaviour could not be observed within our
simulation time. Our results suggest that initial tumbling motion is only
transient in this region of the phase diagram.


title: Instabilities in two flavor quark matter

abstract:
  I discuss briefly the instabilities of two flavor quark matter, paying
attention to the gradient instability which develops in the g2SC phase in the
Goldstone $U(1)_A$ sector.


title:
On the approach to equilibrium for a polymer with adsorption and
  repulsion

abstract:
  We consider paths of a one-dimensional simple random walk conditioned to come
back to the origin after L steps (L an even integer). In the 'pinning model'
each path \eta has a weight \lambda^{N(\eta)}, where \lambda>0 and N(\eta) is
the number of zeros in \eta. When the paths are constrained to be non-negative,
the polymer is said to satisfy a hard-wall constraint. Such models are well
known to undergo a localization/delocalization transition as the pinning
strength \lambda is varied. In this paper we study a natural 'spin flip'
dynamics for these models and derive several estimates on its spectral gap and
mixing time. In particular, for the system with the wall we prove that
relaxation to equilibrium is always at least as fast as in the free case
(\lambda=1, no wall), where the gap and the mixing time are known to scale as
L^{-2} and L^2\log L, respectively. This improves considerably over previously
known results. For the system without the wall we show that the equilibrium
phase transition has a clear dynamical manifestation: for \lambda \geq 1 the
relaxation is again at least as fast as the diffusive free case, but in the
strictly delocalized phase (\lambda < 1) the gap is shown to be O(L^{-5/2}), up
to logarithmic corrections. As an application of our bounds, we prove stretched
exponential relaxation of local functions in the localized regime.


title: From Copenhagen to neo-Copenhagen interpretation

abstract:
  Positive and negative features of the Copenhagen interpretation are
discussed. As positive features can be mentioned its pragmatism and its
awareness of the crucial role of measurement. However, the main part of the
contribution is devoted to the negative features, to wit, its pragmatism (once
again), its confounding of preparation and measurement, its classical account
of measurement, its completeness claims, the ambiguity of its notion of
correspondence, its confused notion of complementarity. It is demonstrated how
confusions and paradoxes stemming from the negative features of the Copenhagen
interpretation can be dealt with in an amended interpretation, to be referred
to as `neo-Copenhagen interpretation', in which the role of the measuring
instrument is taken seriously by recognizing the quantum mechanical character
of its interaction with the microscopic object. The ensuing necessity of
extending the notion of a quantum mechanical observable from the Hermitian
operator of the standard formalism to the positive operator-valued measure of a
generalized formalism is demonstrated to yield a sound mathematical basis for a
transition from the Copenhagen contextualistic-realist interpretation to the
neo-Copenhagen empiricist one. Applications to the uncertainty relations and to
the Bell inequalities are briefly discussed.


title: Electronic superlattices in corrugated graphene

abstract:
  We theoretically investigate electron transport through corrugated graphene
ribbons and show how the ribbon curvature leads to an electronic superlattice
with a period set by the corrugation wave length. Transport through the ribbon
depends sensitively on the superlattice band structure which, in turn, strongly
depends on the geometry of the deformed sheet. In particular, we find that for
ribbon widths where the transverse level separation is comparable to the the
band edge energy, a strong current switching occurs as function of an applied
backgate voltage. Thus, artificially corrugated graphene sheets or ribbons can
be used for the study of Dirac fermions in periodic potentials. Furthermore,
this provides an additional design paradigm for graphene-based electronics.


title:
Bulk Cr tips for scanning tunneling microscopy and spin-polarized
  scanning tunneling microscopy

abstract:
  A simple, reliable method for preparation of bulk Cr tips for Scanning
Tunneling Microscopy (STM) is proposed and its potentialities in performing
high-quality and high-resolution STM and Spin Polarized-STM (SP-STM) are
investigated. Cr tips show atomic resolution on ordered surfaces. Contrary to
what happens with conventional W tips, rest atoms of the Si(111)-7x7
reconstruction can be routinely observed, probably due to a different
electronic structure of the tip apex. SP-STM measurements of the Cr(001)
surface showing magnetic contrast are reported. Our results reveal that the
peculiar properties of these tips can be suited in a number of STM experimental
situations.


title: Entropy production at freeze-out from dissipative fluids

abstract:
  Entropy production due to shear viscosity during the continuous freeze-out of
a longitudinally expanding dissipative fluid is addressed. Assuming the
validity of the fluid dynamical description during the continuous removal of
interacting matter we estimated a small entropy production as function of the
freeze-out duration and the ratio of dissipative to non-dissipative quantities
in case of a relativistic massless pion fluid.


title: On the corotation torque in a radiatively inefficient disk

abstract:
  We consider the angular momentum exchange at the corotation resonance between
a two-dimensional gaseous disk and a uniformly rotating external potential,
assuming that the disk flow is adiabatic. We first consider the linear case for
an isolated resonance, for which we give an expression of the corotation torque
that involves the pressure perturbation, and which reduces to the usual
dependence on the vortensity gradient in the limit of a cold disk. Although
this expression requires the solution of the hydrodynamic equations, it
provides some insight into the dynamics of the corotation region. In the
general case, we find an additional dependence on the entropy gradient at
corotation. This dependence is associated to the advection of entropy
perturbations. These are not associated to pressure perturbations. They remain
confined to the corotation region, where they yield a singular contribution to
the corotation torque. In a second part, we check our torque expression by
means of customized two-dimensional hydrodynamical simulations. In a third
part, we contemplate the case of a planet embedded in a Keplerian disk, assumed
to be adiabatic. We find an excess of corotation torque that scales with the
entropy gradient, and we check that the contribution of the entropy
perturbation to the torque is in agreement with the expression obtained from
the linear analysis. We finally discuss some implications of the corotation
torque expression for the migration of low mass planets in the regions of
protoplanetary disks where the flow is radiatively inefficient on the timescale
of the horseshoe U-turns.


title:
On Frequency Optimisation for Power Saving in WSNs: Finding Optimum
  Hardware Timers Frequencies

abstract:
  Wireless Sensor Networks research and demand are now in full expansion, since
people came to understand these are the key to a large number of issues in
industry, commerce, home automation, healthcare, agriculture and environment,
monitoring, public safety etc. One of the most challenging research problems in
sensor networks research is power awareness and power-saving techniques. In
this master's thesis, we have studied one particular power-saving technique,
i.e. frequency scaling. In particular, we analysed the close relationship
between clock frequencies in a microcontroller and several types of constraints
imposed on these frequencies, e.g. by other components of the microcontroller,
by protocol specifications, by external factors etc. Among these constraints,
we were especially interested in the ones imposed by the timer service and by
the serial ports' transmission rates. Our efforts resulted in a microcontroller
configuration management tool which aims at assisting application programmers
in choosing microcontroller configurations, in function of the particular needs
and constraints of their application.


title:
Comment on "Scaling behavior of classical wave transport in mesoscopic
  media at the localization transition"

abstract:
  We emphasize the importance of the position dependence of the diffusion
coefficient D(r) in the self-consistent theory of localization and argue that
the scaling law T ~ ln(L)/L^2 obtained by Cheung and Zhang [Phys. Rev. B 72,
235102 (2005)] for the average transmission coefficient T of a disordered slab
of thickness L at the localization transition is an artifact of replacing D(r)
by its harmonic mean. The correct scaling T ~ 1/L^2 is obtained by properly
treating the position dependence of D(r).


title: Constituents of the soft X-ray background

abstract:
  The X-ray background is generated by various classes of objects and variety
of emission mechanisms. Relative contribution of individual components depends
on energy. The goal is to assess the integral emission of the major components
of the soft X-ray background (extragalactic discrete sources dominated by AGNs,
galactic plasma, and the Warm/Hot Intergalactic Medium), investigating the
angular structure of the background. Fluctuations of the background are
measured using the auto-correlation function of the XRB determined in 5 energy
bands between 0.3 and 4.5 keV. The investigation is based on the extensive
observational data set selected from the XMM-Newton archives. Amplitudes of the
auto-correlation functions calculated in three energy bands above ~1 keV are
consistent with the conjecture that the background fluctuations result solely
from clustering of sources which produce the background. At energies below 1
keV the relative fluctuation amplitude decreases indicating that a fraction of
the soft XRB is associated with a smooth plasma emission in the Galaxy. It is
shown, however, that the mean spectrum of extragalactic discrete sources
steepens in the soft X-rays and is not well represented by a single power law
in the energy range 0.3-4.5 keV. The WHIM contribution to the total background
fluctuations is small and consistent with the WHIM properties derived from the
cross-correlation of the XRB with galaxies.


title: BCS-BEC crossover in a random external potential

abstract:
  We investigate the ground state properties of a disordered superfluid Fermi
gas across the BCS-BEC (Bose Einstein condensate) crossover. We show that, for
weak disorder, both the depletion of the condensate fraction of pairs and the
normal fluid density exhibit a nonmonotonic behavior as a function of the
interaction parameter $1/k_Fa$, reaching their minimum value near unitarity. We
find that, moving away from the weak coupling BCS regime, Anderson's theorem
ceases to apply and the superfluid order parameter is more and more affected by
the random potential.


title:
Decoherence induced by a dynamic spin environment (I): The universal
  regime

abstract:
  This article analyzes the decoherence induced on a single qubit by the
interaction with a spin chain with nontrivial internal dynamics (XY-type
interactions). The aim of the paper is to study the existence and properties of
the so-called universal regime, in which the decoherence time scale becomes
independent of the strength of the coupling with the environment. It is shown
that although such regime does exist, as previously established by Cucchietti
\textit{et al} in {\em Phys. Rev. A}, 75:032337 (2007), it is not a clear
signature of a quantum phase transition in the environment. In fact, this kind
of universality also exists in the absence of quantum phase transitions. A
universal regime can be related to the existence of an energy scale separation
between the Hamiltonian of the environment and the one characterizing the
system-environment interaction. The results presented also indicate that in the
strong coupling regime the quantum phase transition does not produce an
enhancement of decoherence (as opposed to what happens in the weak coupling
regime).


title:
Qudits of composite dimension, mutually unbiased bases and projective
  ring geometry

abstract:
  The $d^2$ Pauli operators attached to a composite qudit in dimension $d$ may
be mapped to the vectors of the symplectic module $\mathcal{Z}_d^{2}$
($\mathcal{Z}_d$ the modular ring). As a result, perpendicular vectors
correspond to commuting operators, a free cyclic submodule to a maximal
commuting set, and disjoint such sets to mutually unbiased bases. For
dimensions $d=6,~10,~15,~12$, and 18, the fine structure and the incidence
between maximal commuting sets is found to reproduce the projective line over
the rings $\mathcal{Z}_{6}$, $\mathcal{Z}_{10}$, $\mathcal{Z}_{15}$,
$\mathcal{Z}_6 \times \mathbf{F}_4$ and $\mathcal{Z}_6 \times \mathcal{Z}_3$,
respectively.


title: Resonant normal form for even periodic FPU chains

abstract:
  In this paper we investigate periodic FPU chains with an even number of
particles. We show that near the equilibrium point, any such chain admits a
\emph{resonant} Birkhoff normal form of order four which is \emph{completely
integrable} - an important fact which helps explain the numerical experiments
of Fermi, Pasta, and Ulam. We analyze the moment map of the integrable
approximation of an even FPU chain. Unlike in the case of odd FPU chains these
integrable systems (generically) exhibit hyperbolic dynamics. As an application
we prove that any FPU chain with Dirichlet boundary conditions admits a
Birkhoff normal form up to order four and show that a KAM theorem applies.


title: Search for new physics in top events with the D0 detector

abstract:
  This review is focused on the search for new processes, performed with top
quark events in D{\O}. It presents four updated or new D{\O} results. The two
first analyses deal with top production properties: they search for a new heavy
resonance decaying to top-antitop. The two last results concern top decay
properties: the measurement of the $W$ helicity as a probe of the $tWb$
coupling structure, and the top quark branching ratio to $Wb$. Neither of these
measurements reveal any deviation with respect to the standard model
predictions.


title: Near-Zero Modes in Superconducting Graphene

abstract:
  Vortices in the simplest superconducting state of graphene contain very low
energy excitations, whose existence is connected to an index theorem that
applies strictly to an approximate form of the relevant Bogoliubov-deGennes
equations. When Zeeman interactions are taken into account, the zero modes
required by the index theorem are (slightly) displaced. Thus the vortices
acquire internal structure, that plausibly supports interesting dynamical
phenomena.


title:
Non-circular semiconductor nanorings of type I and II: Emission kinetics
  in the exciton Aharonov-Bohm effect

abstract:
  Transition energies and oscillator strengths of excitons in dependence on
magnetic field are investigated in type I and II semiconductor nanorings. A
slight deviation from circular (concentric) shape of the type II nanoring gives
a better observability of the Aharonov-Bohm oscillations since the ground state
is always optically active. Kinetic equations for the exciton occupation are
solved with acoustic phonon scattering as the major relaxation process, and
absorption and luminescence spectra are calculated showing deviations from
equilibrium. The presence of a non-radiative exciton decay leads to a quenching
of the integrated photoluminescence with magnetic field.


title: Isothermal Plasma Waves in Gravitomagnetic Planar Analogue

abstract:
  We investigate the wave properties of the Kerr black hole with isothermal
plasma using 3+1 ADM formalism. The corresponding Fourier analyzed perturbed
GRMHD equations are used to obtain the dispersion relations. These relations
lead to the real values of the components of wave vector $\textbf{k}$ which are
used to evaluate the quantities like phase and group velocities etc. These have
been discussed graphically in the neighborhood of the pair production region.
The results obtained verify the conclusion of Mackay et al. according to which
rotation of a black hole is required for negative phase velocity propagation.


title: Model-independent WIMP Searches at the ILC

abstract:
  We investigate the possibility to detect WIMPs at the ILC in a
model-independent way using events with single photons. The study is done with
a full detector simulation of the LDC detector and MarlinReco. It turns out
that WIMPs are observable this way at the ILC if their coupling to electrons is
not too small. Beam polarisation can increase the accessible phase space
significantly.


title: Evolution of community structure in the world trade web

abstract:
  In this note we study the bilateral merchandise trade flows between 186
countries over the 1948-2005 period using data from the International Monetary
Fund. We use Pajek to identify network structure and behavior across thresholds
and over time. In particular, we focus on the evolution of trade "islands" in
the a world trade network in which countries are linked with directed edges
weighted according to fraction of total dollars sent from one country to
another. We find mixed evidence for globalization.


title: Magnetic properties of two-phase superconductors

abstract:
  We have recently proposed a theoretical model for superconductors endowed
with two distinct superconducting phases, described by two scalar order
parameters which condensate at different critical temperatures. On analyzing
the magnetic behavior of such systems, we have found some observable
differences with respect to the case of ordinary Ginzburg-Landau
superconductors. In particular, at low temperature the London penetration
length is strongly reduced and the Ginzburg-Landau parameter k becomes a
function of temperature. By contrast, in the temperature region between the two
phase transitions k is constant and the system is a type-I or a type-II
superconductor depending on the ratio between the critical temperatures.


title: Nonrelativistic Lee model in three dimensional Riemannian manifolds

abstract:
  In this work, we construct the non-relativistic Lee model on some class of
three dimensional Riemannian manifolds by following a novel approach introduced
by S. G. Rajeev hep-th/9902025. This approach together with the help of heat
kernel allows us to perform the renormalization non-perturbatively and
explicitly. For completeness, we show that the ground state energy is bounded
from below for different classes of manifolds, using the upper bound estimates
on the heat kernel. Finally, we apply a kind of mean field approximation to the
model for compact and non-compact manifolds separately and discover that the
ground state energy grows linearly with the number of bosons n.


title:
Polar supermultiplets, Hermitian symmetric spaces and hyperkahler
  metrics

abstract:
  We address the construction of four-dimensional N=2 supersymmetric nonlinear
sigma models on tangent bundles of arbitrary Hermitian symmetric spaces
starting from projective superspace. Using a systematic way of solving the
(infinite number of) auxiliary field equations along with the requirement of
supersymmetry, we are able to derive a closed form for the Lagrangian on the
tangent bundle and to dualize it to give the hyperkahler potential on the
cotangent bundle. As an application, the case of the exceptional symmetric
space E_6/SO(10) \times U(1) is explicitly worked out for the first time.


title:
Entropy production by Q-ball decay for diluting long-lived charged
  particles

abstract:
  The cosmic abundance of a long-lived charged particle such as a stau is
tightly constrained by the catalyzed big bang nucleosynthesis. One of the ways
to evade the constraints is to dilute those particles by a huge entropy
production. We evaluate the dilution factor in a case that non-relativistic
matter dominates the energy density of the universe and decays with large
entropy production. We find that large Q balls can do the job, which is
naturally produced in the gauge-mediated supersymmetry breaking scenario.


title: Non-Blocking Signature of very large SOAP Messages

abstract:
  Data transfer and staging services are common components in Grid-based, or
more generally, in service-oriented applications. Security mechanisms play a
central role in such services, especially when they are deployed in sensitive
application fields like e-health. The adoption of WS-Security and related
standards to SOAP-based transfer services is, however, problematic as a
straightforward adoption of SOAP with MTOM introduces considerable
inefficiencies in the signature generation process when large data sets are
involved. This paper proposes a non-blocking, signature generation approach
enabling a stream-like processing with considerable performance enhancements.


title:
Controlled deflection of cold atomic clouds and of Bose-Einstein
  condensates

abstract:
  We present a detailed, realistic proposal and analysis of the implementation
of a cold atom deflector using time-dependent far off-resonance optical guides.
An analytical model and numerical simulations are used to illustrate its
characteristics when applied to both non-degenerate atomic ensembles and to
Bose-Einstein condensates. Using for all relevant parameters values that are
achieved with present technology, we show that it is possible to deflect almost
entirely an ensemble of $^{87}$Rb atoms falling in the gravity field. We
discuss the limits of this proposal, and illustrate its robustness against
non-adiabatic transitions.


title: Comment on "Berry Phase in a Composite System"

abstract:
  We show in this comment that the results obtained in a recent work by Yi et
al. [Phys. Rev. Lett. 92, 150406 (2004)] are quantitatively not correct and the
proposed subsystem Berry phase is not well-defined.


title: Characterization of substitution invariant 3iet words

abstract:
  We study infinite words coding an orbit under an exchange of three intervals
which have full complexity $\C(n)=2n+1$ for all $n\in\N$ (non-degenerate 3iet
words). In terms of parameters of the interval exchange and the starting point
of the orbit we characterize those 3iet words which are invariant under a
primitive substitution. Thus, we generalize the result recently obtained for
sturmian words.


title: Work fluctuations in quantum spin chains

abstract:
  We study the work fluctuations of two types of finite quantum spin chains
under the application of a time-dependent magnetic field in the context of the
fluctuation relation and Jarzynski equality. The two types of quantum chains
correspond to the integrable Ising quantum chain and the nonintegrable XX
quantum chain in a longitudinal magnetic field. For several magnetic field
protocols, the quantum Crooks and Jarzynski relations are numerically tested
and fulfilled. As a more interesting situation, we consider the forcing regime
where a periodic magnetic field is applied. In the Ising case we give an exact
solution in terms of double-confluent Heun functions. We show that the
fluctuations of the work performed by the external periodic drift are maximum
at a frequency proportional to the amplitude of the field. In the nonintegrable
case, we show that depending on the field frequency a sharp transition is
observed between a Poisson-limit work distribution at high frequencies toward a
normal work distribution at low frequencies.


title:
Neutrino Triggered Target of Opportunity (NToO) test run with AMANDA-II
  and MAGIC

abstract:
  Kilometer scale neutrino telescopes are now being constructed (IceCube) and
designed (KM3NeT). While no neutrino flux of cosmic origin has been discovered
so far, the first weak signals are expected to be discerned in the next few
years. Multi-messenger (observations combining different kinds of emission)
investigations can enhance the discovery chance for neutrinos in case of
correlations. One possible application is the search for time correlations of
high energy neutrinos and established signals. We show the first adaptation of
a Target of Opportunity strategy to collect simultaneous data of high energy
neutrinos and gamma-rays. Neutrino events with coordinates close to preselected
candidate sources are used to alert gamma-ray observations. The detection of a
positive coincidence can enhance the neutrino discovery chance. More generally,
this scheme of operation can increase the availability of simultaneous
observations. If cosmic neutrino signals can be established, the combined
observations will allow time correlation studies and therefore constraints on
the source modeling. A first technical implementation of this scheme involving
AMANDA-II and MAGIC has been realized for few pre-selected sources in a short
test run (Sept. to Dec. 2006), showing the feasability of the concept. Results
from this test run are shown.


title:
Scanning tunnelling spectroscopy of the vortex state in NbSe2 using a
  superconducting tip

abstract:
  The vortex electronic structure in the multiband superconductor NbSe2 is
studied by means of Scanning Tunneling Spectroscopy (STS) using a
superconducting tip. The use of a superconducting tip (Pb) as a probe provides
an enhancement of the different features related to the DOS of NbSe2 in the
tunneling conductance curves. This use allows the observation of rich patterns
of electronic states in the conductance images around the vortex cores in a
wide range of temperature, as well as the simultaneous acquisition of Josephson
current images in the vortex state.


title:
Techniques, advances, problems and issues in numerical modelling of
  landslide hazard

abstract:
  Slope movements (e.g. landslides) are dynamic systems that are complex in
time and space and closely linked to both inherited and current preparatory and
triggering controls. It is not yet possible to assess in all cases conditions
for failure, reactivation and rapid surges and successfully simulate their
transient and multi-dimensional behaviour and development, although
considerable progress has been made in isolating many of the key variables and
elementary mechanisms and to include them in physically-based models for
landslide hazard assessments. Therefore, the objective of this paper is to
review the state-of-the-art in the understanding of landslide processes and to
identify some pressing challenges for the development of our modelling
capabilities in the forthcoming years for hazard assessment. This paper focuses
on the special nature of slope movements and the difficulties related to
simulating their complex time-dependent behaviour in mathematical,
physically-based models. It analyses successively the research frontiers in the
recognition of first-time failures (pre-failure and failure stages),
reactivation and the catastrophic transition to rapid gravitational processes
(post-failure stage). Subsequently, the paper discusses avenues to transfer
local knowledge on landslide activity to landslide hazard forecasts on regional
scales and ends with an outline how geomorphological investigations and
supporting monitoring techniques could be applied to improve the theoretical
concepts and the modelling performance of physically-based landslide models at
different spatial and temporal scales.


title:
Decoherence induced by a dynamic spin environment (II): Disentanglement
  by local system-environment interactions

abstract:
  This article studies the decoherence induced on a system of two qubits by
local interactions with a spin chain with nontrivial internal dynamics
(governed by an XY Hamiltonian). Special attention is payed to the transition
between two limits: one in which both qubits interact with the same site of the
chain and another one where they interact with distant sites. The two cases
exhibit different behaviours in the weak and strong coupling regimes: when the
coupling is weak it is found that decoherence tends to decrease with distance,
while for strong coupling the result is the opposite. Also, in the weak
coupling case, the long distance limit is rapidly reached, while for strong
coupling there is clear evidence of an expected effect: environment-induced
interactions between the qubits of the system. A consequence of this is the
appearance of quasiperiodic events that can be interpreted as ``sudden deaths''
and ``sudden revivals'' of the entanglement between the qubits, with a time
scale related to the distance between them.


title:
Totally geodesic submanifolds of the complex and the quaternionic
  2-Grassmannians

abstract:
  In this article, I classify the totally geodesic submanifolds in the complex
2-Grassmannians and in the quaternionic 2-Grassmannians. It turns out that for
both of these spaces, the earlier classification of maximal totally geodesic
submanifolds in Riemannian symmetric spaces of rank 2, published by Chen and
Nagano (B.-Y. Chen, T. Nagano, "Totally geodesic submanifolds of symmetric
spaces, II", Duke Math. J. 45 (1978), 405--425) is incomplete.
  For example, G_2(H^n) with n >= 7 contains totally geodesic submanifolds
isometric to a HP^2, its metric scaled such that the minimal sectional
curvature is 1/5; they are maximal in G_2(H^7). Also G_2(C^n) with n >= 6
contains totally geodesic submanifolds which are isometric to a CP^2 contained
in the HP^2 mentioned above; they are maximal in G_2(C^6). Neither submanifolds
are mentioned in the cited paper by Chen and Nagano.


title:
Solvable model for pair excitation in trapped Boson gas at zero
  temperature

abstract:
  In Bose-Einstein condensation, a macroscopically large number of particles
occupy the same single-particle quantum state. Our goal is to study
time-dependent aspects of particle excitations to states other than the
single-particle macroscopic state in trapped dilute atomic gases. We adopt the
view that atoms are excited in pairs so that their scattering from the
single-particle state to vector positions x and y at time t is described by the
pair-excitation function, K0(x,y,t). We solve a nonlocal equation for K0 under
a slowly varying external potential by assuming that the wave function of the
macroscopic state satisfies a time-independent nonlinear Schroedinger equation.
For zero initial excitation (K0=0 at t=0) and sufficiently large t, we evaluate
asymptotically K0 in terms of the one-variable Lommel function for any distance
|x-y|.


title: Markov models for accumulating mutations

abstract:
  We introduce and analyze a waiting time model for the accumulation of genetic
changes. The continuous time conjunctive Bayesian network is defined by a
partially ordered set of mutations and by the rate of fixation of each
mutation. The partial order encodes constraints on the order in which mutations
can fixate in the population, shedding light on the mutational pathways
underlying the evolutionary process. We study a censored version of the model
and derive equations for an EM algorithm to perform maximum likelihood
estimation of the model parameters. We also show how to select the maximum
likelihood poset. The model is applied to genetic data from different cancers
and from drug resistant HIV samples, indicating implications for diagnosis and
treatment.