title: Uniqueness of the EPR--chemeleon model

abstract:
  A classical deterministic, reversible dynamical systems, reproducing the
Einstein--Podolsky--Rosen (EPR) correlations in full respect of causality and
locality and without the introduction of any ad hoc selection procedure, was
constructed in the paper [AIR02].
  In the present paper we prove that the above mentioned model is unique (see
Theorem (2) in the sense that any local causal probability measure which
reproduces the EPR correlations must coincide, under natural and generic
assumptions, with the one constructed in [AIR02].
  [AIR02] L. Accardi, K. Imafuku and M. Regoli, "ON THE EPR--CHAMELEON
EXPERIMENT", Infinite Dimensional Analysis, Quantum Probability and Related
Topics, vol. 5 (2002) 1--20.


title:
Study of the structural changes in the Popocatepetl volcano in Mexico
  related to microseismicity by applying the lineament analysis to the Aster
  (Terra) satellite data

abstract:
  Mexico is one of the most volcanically active regions in North America.
Volcanic activity in central Mexico is associated with the subduction of the
Cocos and Rivera plates beneath the North American plate. Periods of enhanced
microseismic activity, associated with the volcanic activity of the
Popocatepetl volcano is compared with periods, during which the microseismic
activity was low. We detected systematical changes in the number of lineaments,
associated with the microseismic activity due to lineament analysis of a
temporal sequence of high resolution satellite images of the Popocatepetl
volcano, provided by the ASTER/VNIR instrument. The Lineament Extraction and
Stripes Statistic Analysis (LESSA) software package was used for the lineament
extraction. In the future it would allow develop a methodology for detection of
possible elevation of pressure in volcano edifice.


title: Entanglement measures and approximate quantum error correction

abstract:
  It is shown that, if the loss of entanglement along a quantum channel is
sufficiently small, then approximate quantum error correction is possible,
thereby generalizing what happens for coherent information. Explicit bounds are
obtained for the entanglement of formation and the distillable entanglement,
and their validity naturally extends to other bipartite entanglement measures
in between. Robustness of derived criteria is analyzed and their tightness
compared. Finally, as a byproduct, we prove a bound quantifying how large the
gap between entanglement of formation and distillable entanglement can be for
any given finite dimensional bipartite system, thus providing a sufficient
condition for distillability in terms of entanglement of formation.


title:
Excitation energies, polarizabilities, multipole transition rates, and
  lifetimes of ions along the francium isoelectronic sequence

abstract:
  Relativistic many-body perturbation theory is applied to study properties of
ions of the francium isoelectronic sequence. Specifically, energies of the 7s,
7p, 6d, and 5f states of Fr-like ions with nuclear charges Z = 87 - 100 are
calculated through third order; reduced matrix elements, oscillator strengths,
transition rates, and lifetimes are determined for 7s - 7p, 7p - 6d, and 6d -
5f electric-dipole transitions; and 7s - 6d, 7s - 5f, and 5f_5/2 - 5f_7/2
multipole matrix elements are evaluated to obtain the lifetimes of low-lying
excited states. Moreover, for the ions Z = 87 - 92 calculations are also
carried out using the relativistic all-order single-double method, in which
single and double excitations of Dirac-Fock wave functions are included to all
orders in perturbation theory. With the aid of the SD wave functions, we obtain
accurate values of energies, transition rates, oscillator strengths, and the
lifetimes of these six ions. Ground state scalar polarizabilities in Fr I, Ra
II, Ac III, and Th IV are calculated using relativistic third-order and
all-order methods. Ground state scalar polarizabilities for other Fr-like ions
are calculated using a relativistic second-order method. These calculations
provide a theoretical benchmark for comparison with experiment and theory.


title:
Characters of representations of affine Kac-Moody Lie algebras at the
  critical level

abstract:
  We present an explicit character formula for the irreducible highest weight
representations of the non-twisted affine Kac-Moody Lie algebra at the critical
level which are integrable over the corresponding finite-dimensional simple Lie
algebra.


title: Ultra-relativistic geometrical shock dynamics and vorticity

abstract:
  Geometrical shock dynamics, also called CCW theory, yields approximate
equations for shock propagation in which only the conditions at the shock
appear explicitly; the post-shock flow is presumed approximately uniform and
enters implicitly via a Riemann invariant. The nonrelativistic theory,
formulated by G. B. Whitham and others, matches many experimental results
surprisingly well. Motivated by astrophysical applications, we adapt the theory
to ultra-relativistic shocks advancing into an ideal fluid whose pressure is
negligible ahead of the shock, but one third of its proper energy density
behind the shock. Exact results are recovered for some self-similar cylindrical
and spherical shocks with power-law pre-shock density profiles. Comparison is
made with numerical solutions of the full hydrodynamic equations. We review
relativistic vorticity and circulation. In an ultrarelativistic ideal fluid,
circulation can be defined so that it changes only at shocks, notwithstanding
entropy gradients in smooth parts of the flow.


title:
Production of magnetic energy by macroscopic turbulence in GRB
  afterglows

abstract:
  Afterglows of gamma-ray bursts are believed to require magnetic fields much
stronger than that of the compressed pre-shock medium. As an alternative to
microscopic plasma instabilities, we propose amplification of the field by
macroscopic turbulence excited by the interaction of the shock with a clumpy
pre-shock medium, for example a stellar wind. Using a recently developed
formalism for localized perturbations to an ultra-relativistic shock, we derive
constraints on the lengthscale, amplitude, and volume filling factor of density
clumps required to produce a given magnetic energy fraction within the
expansion time of the shock, assuming that the energy in the field achieves
equipartion with the turbulence. Stronger and smaller-scale inhomogeneities are
required for larger shock Lorentz factors. Hence it is likely that the magnetic
energy fraction evolves as the shock slows. This could be detected by
monitoring the synchrotron cooling frequency if the radial density profile
ahead of the shock, smoothed over clumps, is known.


title:
The Pseudo-Newtonian Force and Potential about a Higher Dimensional
  Rotating Black Hole

abstract:
  In this paper, we study the behavior of the pseudo-Newtonian force and
potential about a higher dimensional rotating black hole. We obtain conditions
for the force character from an attractive to repulsive. We also find the
conditions under which force attains a maximum value. The results of this paper
generalizes the already found structure of force and potential about a five
dimensional rotating black hole. It is interesting to note that we recover the
five dimensional results under a special case.


title:
Holographic storage of multiple coherence gratings in a Bose-Einstein
  condensate

abstract:
  We demonstrate superradiant conversion between a two-mode collective atomic
state and a single-mode light field in an elongated cloud of Bose-condensed
atoms. Two off-resonant write beams induce superradiant Raman scattering,
producing two independent coherence gratings with a different wave vector in
the cloud. By applying phase-matched read beams after a controllable delay, the
gratings can be selectively converted into the light field also in a
superradiant way. Due to the large cooperativity parameter and the small
velocity width of the condensate, a high conversion efficiency of $> 70$ % and
a long storage time of $> 120$ $\mu$s were achieved.


title: Comments on Controllable Three-Dimensional Brownian Motors

abstract:
  Upon reviewing the physical review letter which describes the processes
involved in "demonstration of a controllable three-dimensional Brownian motor
in symmetric potentials" we conclude that such processes are not compatible
with what Einstein and many other physicists and engineers define as Brownian
motors or Brownian movements.


title: On the scalar nonet in the extended Nambu Jona-Lasinio model

abstract:
  We discuss the lightest scalar resonances, $f_0(600)$, $\kappa(800)$,
$a_0(980)$ and $f_0(980)$ in the extended Nambu Jona-Lasinio model. We find
that the model parameters can be tuned, but unnaturally, to accommodate for
those scalars except the $f_0(980)$. We also discuss problems encountered in
the K Matrix unitarization approximation by using $N_c$ counting technique.


title: TASI Lectures on Astrophysical Aspects of Neutrinos

abstract:
  Neutrino astronomy is on the verge of discovering new sources, and this will
lead to important advances in astrophysics, cosmology, particle physics, and
nuclear physics. This paper is meant for non-experts, so that they might better
understand the basic issues in this field.


title: Forbidden territories in the string landscape

abstract:
  Problems of stabilizing moduli of the type--IIB string theory on toroidal
orientifolds $\T^6/\Z_2$, in presence of worldvolume fluxes on various
D-branes, are considered. For $Z_2$ actions, introducing either O9 or O3
planes, we rule out the possibility of moduli stabilization in a wide class of
models with $\mathcal{N}=1$ supersymmetry, characterized by the type of fluxes
turned on along D-brane worldvolume. Our results, in particular, imply that
Abelian worldvolume fluxes can not by themselves stabilize closed string
moduli, in a consistent supersymmtric model, for above orientifold
compactifications. We also discuss other $Z_2$ orientifolds of $T^6$ and show
that certain other brane wrappings are also ruled out by similar consistency
requirements. In specific setups we consider examples with D9-branes wrapping
on a complex three-torus with its world-volume fluxes taken to be
semi-homogeneous bundles and D7-branes wrapping holomorphic four-cycles of the
complex three-torus carrying world-volume fluxes.


title: A Family of Exactly-Solvable Driven-Diffusive Systems in One-dimension

abstract:
  We introduce an exactly-solvable family of one-dimensional driven-diffusive
systems defined on a discrete lattice. We find the quadratic algebra of this
family which has an infinite-dimensional representation. We discuss the phase
diagram of the system in a couple of special cases.


title:
Use of high resolution satellite images for tracking of changes in the
  lineament structure, caused by earthquakes

abstract:
  Over the last decades strong efforts have been made to apply new spaceborn
technologies to the study and possible forecast of strong earthquakes. In this
study we use ASTER/TERRA multispectral satellite images for detection and
analysis of changes in the system of lineaments previous to a strong
earthquake. A lineament is a straight or a somewhat curved feature in an image,
which it is possible to detect by a special processing of images based on
directional filtering and or Hough transform. "The Lineament Extraction and
Stripes Statistic Analysis" (LESSA) software package, developed by Zlatopolsy
(1992, 1997). We assume that the lineaments allow to detect, at least
partially, the presence ruptures in the Earths crust, and therefore enable one
to follow the changes in the system of faults and fractures associated with
strong earthquakes. We analysed 6 earthquakes occurred in the Pacific coast of
the South America and XXX with the Richter scale magnitude >4.5. They were
located in the regions with small seasonal variations and limited vegetation to
facilitate the tracking of features associated with the seismic activity only.
It was found that the number and orientation of lineaments changed
significantly about one month before an earthquake approximately, and a few
months later the system returns to its initial state. This effect increases
with the earthquake magnitude, and it is much more easily detectable in case of
convergent plate boundaries (for example, Nasca and South American plates). The
results obtained open a possibility to develop a methodology able to evaluate
the seismic risk in the regions with similar geological conditions.


title:
Chandra Observations of SN 2004et and the X-ray Emission of Type IIp
  Supernovae

abstract:
  We report the X-ray detection of the Type II-plateau supernova SN 2004et in
the spiral galaxy NGC 6946, using the Chandra X-Ray Observatory. The position
of the X-ray source was found to agree with the optical position within ~0.4
arcsec. Chandra also surveyed the region before the 2004 event, finding no
X-ray emission at the location of the progenitor. For the post-explosion
observations, a total of 202, 151, and 158 photons were detected in three
pointings, each ~29 ks in length, on 2004 October 22, November 6, and December
3, respectively. The spectrum of the first observation is best fit by a thermal
model with a temperature of kT=1.3 keV and a line-of-sight absorption of
N_H=1.0 x 10^{22} cm^{-2}. The inferred unabsorbed luminosity (0.4-8 keV) is
~4x10^{38} erg/s, adopting a distance of 5.5 Mpc. A comparison between hard and
soft counts on the first and third epochs indicates a softening over this time,
although there is an insufficient number of photons to constrain the variation
of temperature and absorption by spectral fitting. We model the emission as
arising from the reverse shock region in the interaction between the supernova
ejecta and the progenitor wind. For a Type IIP supernova with an extended
progenitor, the cool shell formed at the time of shock wave breakout from the
star can affect the initial evolution of the interaction shell and the
absorption of radiation from the reverse shock. The observed spectral softening
might be due to decreasing shell absorption. We find a pre-supernova mass loss
rate of (2-2.5)x 10^{-6} M_{\odot} /yr for a wind velocity of 10 kms, which is
in line with expectations for a Type IIP supernova.


title: Neutrino mass in radiatively-broken scale-invariant models

abstract:
  Scale invariance may be a classical symmetry which is broken radiatively.
This provides a simple way to stabilize the scale of electroweak symmetry
breaking against radiative corrections. The simplest phenomenologically
successful model of this type involves the addition of one real scalar field to
the standard model. In this minimal model the electroweak Higgs can be
interpreted as the pseudo-Goldstone boson of broken scale invariance. We study
the possible origin of neutrino mass in such models, both at tree-level and
radiatively.


title:
Exact solutions for the Einstein-Gauss-Bonnet theory in five dimensions:
  Black holes, wormholes and spacetime horns

abstract:
  An exhaustive classification of certain class of static solutions for the
five-dimensional Einstein-Gauss-Bonnet theory in vacuum is presented. The class
of metrics under consideration is such that the spacelike section is a warped
product of the real line with a nontrivial base manifold. It is shown that for
generic values of the coupling constants the base manifold must be necessarily
of constant curvature, and the solution reduces to the topological extension of
the Boulware-Deser metric. It is also shown that the base manifold admits a
wider class of geometries for the special case when the Gauss-Bonnet coupling
is properly tuned in terms of the cosmological and Newton constants. This
freedom in the metric at the boundary, which determines the base manifold,
allows the existence of three main branches of geometries in the bulk. For
negative cosmological constant, if the boundary metric is such that the base
manifold is arbitrary, but fixed, the solution describes black holes whose
horizon geometry inherits the metric of the base manifold. If the base manifold
possesses a negative constant Ricci scalar, two different kinds of wormholes in
vacuum are obtained. For base manifolds with vanishing Ricci scalar, a
different class of solutions appears resembling "spacetime horns". There is
also a special case for which, if the base manifold is of constant curvature,
due to certain class of degeneration of the field equations, the metric admits
an arbitrary redshift function. For wormholes and spacetime horns, there are
regions for which the gravitational and centrifugal forces point towards the
same direction. All these solutions have finite Euclidean action, which reduces
to the free energy in the case of black holes, and vanishes in the other cases.
Their mass is also obtained from a surface integral.


title:
Single quantum dot spectroscopy using a fiber taper waveguide near-field
  optic

abstract:
  Photoluminescence spectroscopy of single InAs quantum dots at cryogenic
temperatures (~14 K) is performed using a micron-scale optical fiber taper
waveguide as a near-field optic. The measured collection efficiency of quantum
dot spontaneous emission into the fundamental guided mode of the fiber taper is
estimated at 0.1%, and spatially-resolved measurements with ~600 nm resolution
are obtained by varying the taper position with respect to the sample and using
the fiber taper for both the pump and collection channels.


title:
Adiabatic quantum dynamics of a random Ising chain across its quantum
  critical point

abstract:
  We present here our study of the adiabatic quantum dynamics of a random Ising
chain across its quantum critical point. The model investigated is an Ising
chain in a transverse field with disorder present both in the exchange coupling
and in the transverse field. The transverse field term is proportional to a
function $\Gamma(t)$ which, as in the Kibble-Zurek mechanism, is linearly
reduced to zero in time with a rate $\tau^{-1}$, $\Gamma(t)=-t/\tau$, starting
at $t=-\infty$ from the quantum disordered phase ($\Gamma=\infty$) and ending
at $t=0$ in the classical ferromagnetic phase ($\Gamma=0$). We first analyze
the distribution of the gaps -- occurring at the critical point $\Gamma_c=1$ --
which are relevant for breaking the adiabaticity of the dynamics. We then
present extensive numerical simulations for the residual energy $E_{\rm res}$
and density of defects $\rho_k$ at the end of the annealing, as a function of
the annealing inverse rate $\tau$. %for different lenghts of the chain. Both
the average $E_{\rm res}(\tau)$ and $\rho_k(\tau)$ are found to behave
logarithmically for large $\tau$, but with different exponents, $[E_{\rm
res}(\tau)/L]_{\rm av}\sim 1/\ln^{\zeta}(\tau)$ with $\zeta\approx 3.4$, and
$[\rho_k(\tau)]_{\rm av}\sim 1/\ln^{2}(\tau)$. We propose a mechanism for
$1/\ln^2{\tau}$-behavior of $[\rho_k]_{\rm av}$ based on the Landau-Zener
tunneling theory and on a Fisher's type real-space renormalization group
analysis of the relevant gaps. The model proposed shows therefore a
paradigmatic example of how an adiabatic quantum computation can become very
slow when disorder is at play, even in absence of any source of frustration.


title:
An elementary proof of global existence for nonlinear wave equations in
  an exterior domain

abstract:
  The aim of this article is to present an elementary proof of a global
existence result for nonlinear wave equations satifying the null condition in
an exterior domain. The novelty of our proof is to avoid completely the scaling
operator which would make the argument complicated in the mixed problem, by
using a new weighted pointwise estimates of a tangential derivative to the
light cone.


title: Near-infrared Study of the Carina Nebula

abstract:
  We have carried out near-infrared (NIR) imaging observations of the Carina
Nebula for an area of ~400 sq. arcmin. including the star clusters Trumpler 14
(Tr 14) and Trumpler 16 (Tr 16). With 10 sigma limiting magnitudes of J ~ 18.5,
H ~ 17.5 and K_s ~ 16.5, we identified 544 Class II and 11 Class I young star
candidates. We find some 40 previously unknown very red sources with H-K_s > 2,
most of which remain undetected at the J band. The red NIR sources are found to
be concentrated to the south-east of Tr 16, along the `V' shaped dust lane,
where the next generation of stars seems to be forming. In addition, we find
indications of ongoing star formation near the three MSX point sources,
G287.51-0.49, G287.47-0.54, and G287.63-0.72. A handful of red NIR sources are
seen to populate around each of these MSX sources. Apart from this, we
identified two hard Chandra X-ray sources near G287.47-0.54, one of which does
not have an NIR counterpart and may be associated with a Class I/Class 0
object. The majority of the Class II candidates, on the other hand, are seen to
be distributed in the directions of the clusters, demarcating different
evolutionary stages in this massive star-forming region. A comparison of the
color-magnitude diagrams of the clusters with pre-main sequence model tracks
shows that the stellar population of these clusters is very young (< 3 Myr).
The K_s band luminosity function (KLF) of Tr 14 shows structure at the faint
end, including a sharp peak due to the onset of deuterium burning, implying an
age of 1-2 Myr for the cluster. The KLF of Tr 16, in contrast, is found to rise
smoothly until it turns over. The slopes of the mass functions derived for the
clusters are found to be in agreement with the canonical value of the field
star initial mass function derived by Salpeter.


title: General concepts of graphs

abstract:
  A little general abstract combinatorial nonsense delivered in this note is a
presentation of some old and basic concepts, central to discrete mathematics,
in terms of new words. The treatment is from a structural and systematic point
of view. This note consists essentially of definitions and summaries.


title: Long Memory in Nonlinear Processes

abstract:
  It is generally accepted that many time series of practical interest exhibit
strong dependence, i.e., long memory. For such series, the sample
autocorrelations decay slowly and log-log periodogram plots indicate a
straight-line relationship. This necessitates a class of models for describing
such behavior. A popular class of such models is the autoregressive
fractionally integrated moving average (ARFIMA) which is a linear process.
However, there is also a need for nonlinear long memory models. For example,
series of returns on financial assets typically tend to show zero correlation,
whereas their squares or absolute values exhibit long memory. Furthermore, the
search for a realistic mechanism for generating long memory has led to the
development of other nonlinear long memory models. In this chapter, we will
present several nonlinear long memory models, and discuss the properties of the
models, as well as associated parametric andsemiparametric estimators.


title: Subgeometric ergodicity of Markov chains

abstract:
  The goal of this paper is to give a short and self contained proof of general
bounds for subgeometric rates of convergence, under practical conditions. The
main result whose proof, based on coupling, provides an intuitive understanding
of the results of Nummelin and Tuominen (1983) and Tuominen and Tweedie (1994).
To obtain practical rates, a very general drift condition, recently introduced
in Douc et al (2004) is used.


title: On the K\"ahler classes of constant scalar curvature metrics on blow ups

abstract:
  In this note we clarify the structure of the moduli space of constant scalar
curvature Kaehler metrics as one approaches the boundary of the Kaehler cone on
cscK manifolds blown up at finite set of points, in the spirit of the previous
work arXiv:math/0504115. Results about which Kaehler classes can be reached and
about the position of the blown up points are given.


title: Nurturing Breakthroughs: Lessons from Complexity Theory

abstract:
  A general theory of innovation and progress in human society is outlined,
based on the combat between two opposite forces (conservatism/inertia and
speculative herding "bubble" behavior). We contend that human affairs are
characterized by ubiquitous ``bubbles'', which involve huge risks which would
not otherwise be taken using standard cost/benefit analysis. Bubbles result
from self-reinforcing positive feedbacks. This leads to explore uncharted
territories and niches whose rare successes lead to extraordinary discoveries
and provide the base for the observed accelerating development of technology
and of the economy. But the returns are very heterogeneous, very risky and may
not occur. In other words, bubbles, which are characteristic definitions of
human activity, allow huge risks to get huge returns over large scales. We
outline some underlying mathematical structure and a few results involving
positive feedbacks, emergence, heavy-tailed power laws, outliers/kings/black
swans, the problem of predictability and the illusion of control, as well as
some policy implications.


title: Vortex pump for dilute Bose-Einstein condensates

abstract:
  The formation of vortices by topological phase engineering has been realized
experimentally to create the first two- and four-quantum vortices in dilute
atomic Bose-Einstein condensates [A. E. Leanhardt et al., Phys. Rev. Lett. 89,
190403 (2002)]. We consider a similar system, but in addition to the
Ioffe-Pritchard magnetic trap we employ an additional hexapole field. By
controlling cyclicly the strengths of these magnetic fields, we show that a
fixed amount of vorticity can be added to the condensate in each cycle. In an
adiabatic operation of this vortex pump, the appearance of vortices into the
condensate is interpreted as the accumulation of a local Berry phase. Our
design can be used as an experimentally realizable vortex source for possible
vortex-based applications of dilute Bose-Einstein condensates.


title: Chirality induced anomalous-Hall effect in helical spin crystals

abstract:
  Under pressure, the itinerant helimagnet MnSi displays unusual magnetic
properties. We have previously discussed a BCC helical spin crystal as a
promising starting point for describing the high pressure phenomenology. This
state has topologically nontrivial configurations of the magnetization field.
Here we note the consequences for magneto-transport that arise generally from
such spin textures. In particular a skyrmion density induced `topological' Hall
effect, with unusual field dependence, is described.


title: Do language change rates depend on population size?

abstract:
  An earlier study (Nettle 1999b) concluded, based on computer simulations and
some inferences from empirical data, that languages will change the more slowly
the larger the population gets. We replicate this study using a more complete
language model for simulations (the Schulze model combined with a
Barabasi-Albert net- work) and a richer empirical dataset (the World Atlas of
Language Structures edited by Haspelmath et al. 2005). Our simulations show
either a weak or stronger dependence of language change on population sizes
depending on the parameter settings, and empirical data, like some of the
simulations, show a weak dependence.


title: Generalized Space-time Noncommutative Inflation

abstract:
  We study the noncommutative inflation with a time-dependent noncommutativity
between space and time. From the numerical analysis of power law inflation,
there are clues that the CMB spectrum indicates a nonconstant noncommutative
inflation. Then we extend our treatment to the inflation models with more
general noncommutativity and find that the scalar perturbation power spectrum
depends sensitively on the time varying of the spacetime noncommutativity. This
stringy effect may be probed in the future cosmological observations.


title:
Role of the rho meson in the description of pion electroproduction
  experiments at JLab

abstract:
  We study the p(e,e' pi+)n reaction in the framework of an effective
Lagrangian approach including nucleon, pi and rho meson degrees of freedom and
show the importance of the rho-meson t-pole contribution to sigmaT, the
transverse part of cross section. We test two different field representations
of the rho meson, vector and tensor, and find that the tensor representation of
the rho meson is more reliable in the description of the existing data. In
particular, we show that the rho-meson t-pole contribution, including the
interference with an effective non-local contact term, sufficiently improves
the description of the recent JLab data at invariant mass W less 2.2 GeV and Q2
less 2.5 GeV2/c2. A ``soft'' variant of the strong piNN and rhoNN form factors
is also found to be compatible with these data. On the basis of the successful
description of both the sigmaL and sigmaT parts of the cross section we discuss
the importance of taking into account the sigmaT data when extracting the
charge pion form factor Fpi from sigmaL.


title: Probing Minimal Flavor Violation at the LHC

abstract:
  If the LHC experiments discover new particles that couple to the Standard
Model fermions, then measurements by ATLAS and CMS can contribute to our
understanding of the flavor puzzles. We demonstrate this statement by
investigating a scenario where extra SU(2)-singlet down-type quarks are within
the LHC reach. By measuring masses, production cross sections and relative
decay rates, minimal flavor violation (MFV) can in principle be excluded.
Conversely, these measurements can probe the way in which MFV applies to the
new degrees of freedom. Many of our conclusions are valid in a much more
general context than this specific extension of the Standard Model.


title:
Nonlinear turbulent magnetic diffusion and effective drift velocity of
  large-scale magnetic field in a two-dimensional magnetohydrodynamic
  turbulence

abstract:
  We study a nonlinear quenching of turbulent magnetic diffusion and effective
drift velocity of large-scale magnetic field in a developed two-dimensional MHD
turbulence at large magnetic Reynolds numbers. We show that transport of the
mean-square magnetic potential strongly changes quenching of turbulent magnetic
diffusion. In particularly, the catastrophic quenching of turbulent magnetic
diffusion does not occur for the large-scale magnetic fields $B \gg B_{\rm eq}
/ \sqrt{\rm Rm}$ when a divergence of the flux of the mean-square magnetic
potential is not zero, where $B_{\rm eq}$ is the equipartition mean magnetic
field determined by the turbulent kinetic energy and Rm is the magnetic
Reynolds number. In this case the quenching of turbulent magnetic diffusion is
independent of magnetic Reynolds number. The situation is similar to
three-dimensional MHD turbulence at large magnetic Reynolds numbers whereby the
catastrophic quenching of the alpha effect does not occur when a divergence of
the flux of the small-scale magnetic helicity is not zero.


title: Stationary black holes and attractor mechanism

abstract:
  We investigate the symmetries of the near horizon geometry of extremal
stationary black holes in four dimensional Einstein gravity coupled to abelian
gauge fields and neutral scalars. Careful consideration of the equations of
motion and the boundary conditions at the horizon imply that the near horizon
geometry has $SO(2,1)\times U(1)$ isometry. This complements the rotating
attractors proposal of hep-th/0606244 that had assumed the presence of this
isometry. The extremal solutions are classified into two families
differentiated by the presence or absence of an ergo-region. We also comment on
the attractor mechanism of both branches.


title: Quenching of photon and pion spectra at intermediate RHIC energy

abstract:
  Single prompt photon and pion spectra in p-p and Au-Au collisions at
intermediate RHIC energy, s^1/2 = 62.4 GeV, are computed at large transverse
momentum in perturbative QCD. Next-to-leading order calculations in p-p
scattering are first presented. The quenching of the prompt photon and pion
yield due to energy loss processes in central Au-Au with respect to p-p
collisions is then predicted. At this energy, the small phase-space available
to produce hard partons makes the pion quenching almost as pronounced as at
s^1/2 = 200 GeV, despite the smaller gluon density of the produced medium. In
the photon sector, energy loss effects prove small because of this very
phase-space restriction, which favours the direct production channel. A
significant suppression of high-pt photons is however predicted, because of a
strong isospin effect together with the depletion of nuclear parton densities
at large x.


title: Extreme-Value Analysis of Standardized Gaussian Increments

abstract:
  Let $\{X_i,i=1,2,...\}$ be i.i.d. standard gaussian variables. Let
$S_n=X_1+...+X_n$ be the sequence of partial sums and $$ L_n=\max_{0\leq
i<j\leq n}\frac{S_j-S_i}{\sqrt{j-i}}. $$ We show that the distribution of
$L_n$, appropriately normalized, converges as $n\to\infty$ to the Gumbel
distribution. In some sense, the the random variable $L_n$, being the maximum
of $n(n+1)/2$ dependent standard gaussian variables, behaves like the maximum
of $Hn \log n$ independent standard gaussian variables. Here, $H\in (0,\infty)$
is some constant. We also prove a version of the above result for the Brownian
motion.


title: Casimir-Lifshitz force out of thermal equilibrium

abstract:
  We study the Casimir-Lifshitz interaction out of thermal equilibrium, with
particular attention devoted to the surface-surface and surface-atom
configurations. A systematic investigation of the contributions to the force
coming from the propagating and evanescent components of the electromagnetic
radiation is performed. The large distance behaviors of such interactions is
discussed, and both analytical and numerical results are compared with the
equilibrium ones. A detailed analysis of the crossing between the
surface-surface and the surface-rarefied body, and finally the surface-atom
force is shown, and a complete derivation and discussion of the recently
predicted non-additivity effects and new asymptotic behaviors is presented.


title: On the inspiral of Massive Black Holes in gas-rich galaxy mergers

abstract:
  We present a study on the dynamics of massive BHs in galaxy mergers, obtained
from a series of high-resolution N-Body/SPH simulations. The presence of a
gaseous component is essential for the rapid formation of an eccentric
(Keplerian) BH binary, that resides at the center of a massive (~10^9 Msun)
turbulent nuclear disc. Using physically and/or numerically motivated recipes,
we follow the accretion history of the BHs during the merger. The mass of the
BHs increases as large central inflows of gas occur inside each galaxy, and
their mass ratio varies with time. Given the encountered strong degeneracy
between numerical resolution and physical assumptions, we suggest here three
possible paths followed by the galaxies and the BHs during a merger in order to
fulfill the M-sigma relation : Adjustment, Symbiosis, and BH Dominance. In an
extremely high resolution run, we resolved the turbulent gas pattern down to
parsec scales, and found that BH feedback is expected to be effective near the
end of the merger. We then trace the BH binary orbit down to a scale of 0.1 pc
modeling the nuclear disc as an equilibrium Mestel disc composed either of gas,
gas and stars, or just stars. Under the action of dynamical friction against
the rotating gaseous and/or stellar background the orbit circularizes. When
this occurs, each BH is endowed with its own small-size (~0.01 pc) accretion
disc comprising a few percent of the BH mass. Double AGN activity is expected
to occur on an estimated timescale of ~10 Myrs, comparable to the inspiral
time. The double nuclear point--like sources that may appear have typical
separations of ~10 pc, and are likely to be embedded in the still ongoing
starburst.


title:
Cooperative action in eukaryotic gene regulation: physical properties of
  a viral example

abstract:
  The Epstein-Barr virus (EBV) infects more than 90% of the human population,
and is the cause of several both serious and mild diseases. It is a
tumorivirus, and has been widely studied as a model system for gene
(de)regulation in human. A central feature of the EBV life cycle is its ability
to persist in human B cells in states denoted latency I, II and III. In latency
III the host cell is driven to cell proliferation and hence expansion of the
viral population, but does not enter the lytic pathway, and no new virions are
produced, while the latency I state is almost completely dormant. In this paper
we study a physico-chemical model of the switch between latency I and latency
III in EBV. We show that the unusually large number of binding sites of two
competing transcription factors, one viral and one from the host, serves to
make the switch sharper (higher Hill coefficient), either by cooperative
binding between molecules of the same species when they bind, or by competition
between the two species if there is sufficient steric hindrance.


title:
Development of a 5 MHz frequency difference pre-multiplier for a short
  term frequency stability bench of the oscillators

abstract:
  This paper reports the realization of a 5 MHz frequency difference x10
pre-multiplier, developed in the laboratory to replace an obsolete one. The
principle we chose is to synthesize a 45 MHz and a 50 MHz from a reference
signal and from the signal to be measured, and to subtract one to the other to
generate a 5 MHz, whose precision on the measurement is increased by a factor
10. Obtained Allan variance y() at 1 s is 5.10-14 and output
spectral density of phase noise floor is about -160 dBc/Hz at 5 MHz.


title: Two-particle binding energy of interacting Bose gases

abstract:
  The pole of the two-particle T-matrix including the influence of the
surrounding medium is analyzed for an interacting Bose gas. The phase diagram
of the Bose -Einstein condensation (BEC) depending on the temperature, density,
scattering length, and momentum is derived from this pole. The critical
momentum for the occurrence of superfluidity is obtained in this way. As a new
observation a two- particle binding energy is reported intimately connected
with the occurrence of the BEC. It is suggested that this might have
cosmological consequences on the dark energy problem.

categories: cond-mat.other astro-ph cond-mat.stat-mech cond-mat.str-el gr-qc physics.atom-ph


title:
Connecting N-representability to Weyl's problem: The one particle
  density matrix for N = 3 and R = 6

abstract:
  An analytic proof is given of the necessity of the Borland-Dennis conditions
for 3-representability of a one particle density matrix with rank 6. This may
shed some light on Klyachko's recent use of Schubert calculus to find general
conditions for N-representability.


title: Transition region features observed with Hinode/EIS

abstract:
  Two types of active region feature prominent at transition region
temperatures are identified in Hinode/EIS data of AR 10938 taken on 2007
January 20. The footpoints of 1 MK TRACE loops are shown to emit strongly in
emission lines formed at log T=5.4-5.8, allowing the temperature increase along
the footpoints to be clearly seen. A density diagnostic of Mg VII yields the
density in the footpoints, with one loop showing a decrease from 3x10^9 cm^-3
at the base to 1.5x10^9 cm^-3 at a projected height of 20 Mm. The second
feature is a compact active region transition region brightening which is
particularly intense in O V emission (log T=5.4) but also has a signature at
temperatures up to log T=6.3. The Mg VII diagnostic gives a density of 4x10^10
cm^-3, and emission lines of Mg VI and Mg VII show line profiles broadened by
50 km/s and wings extending beyond 200 km/s. Continuum emission in the short
wavelength band is also found to be enhanced, and is suggested to be free-bound
emission from recombination onto He^+.


title: EUV emission lines and diagnostics observed with Hinode/EIS

abstract:
  Quiet Sun and active region spectra from the Hinode/EIS instrument are
presented, and the strongest lines from different temperature regions
discussed. A list of emission lines recommended to be included in EIS
observation studies is presented based on analysis of blending and diagnostic
potential using the CHIANTI atomic database. In addition we identify the most
useful density diagnostics from the ions covered by EIS.


title:
Advanced bridge instrument for the measurement of the phase noise and of
  the short-term frequency stability of ultra-stable quartz resonators

abstract:
  High-stability quartz oscillators are needed in a number of space
applications. A short-term stability of parts in 10^{-14} [Allan deviation
\sigma y(\tau) ] is sometimes required, for integration time \tau of
approximately 1-10 s. The Centre National d'Etudes Spatiales (CNES) and the
FEMTO-ST Institute (formerly LPMO and LCEP), have been collaborating for many
years in this domain, aiming at measuring and at understanding the oscillator
noise. The highest stability has been observed on 5 MHz and 10 MHz bulk
acoustic-wave resonators. Yet this stability is still not sufficient, or the
the manufacturing method is not reproducible. Recently, the analysis of a few
premium-stability oscillators has demonstrated that the oscillator frequency
instability is due to the fluctuation of the resonator natural frequency,
rather than to the noise of the sustaining amplifier via the Leeson effect. It
is therefore natural to give attention to the measurement of the resonator
fluctuations.


title:
Failure of standard approximations of the exchange coupling in
  nanostructures

abstract:
  We calculate the exchange coupling for a double dot system using a novel,
numerically exact yet efficient technique, based on finite-element methods.
Specifically, we evaluate the exchange coupling both for a quasi-one and a
two-dimensional system, also including an applied magnetic field. Our numerical
results provide a stringent test for standard approximation schemes (e.g.,
Heitler-London, Hund-Mulliken, Hubbard), and they show that the standard
methods do not have reliable predictive power for real quantum-dot systems.


title: FIPA-based Interoperable Agent Mobility Proposal

abstract:
  This paper presents a proposal for a flexible agent mobility architecture
based on IEEE-FIPA standards and intended to be one of them. This proposal is a
first step towards interoperable mobility mechanisms, which are needed for
future agent migration between different kinds of platforms. Our proposal is
presented as a flexible and robust architecture that has been successfully
implemented in the JADE and AgentScape platforms. It is based on an open set of
protocols, allowing new protocols and future improvements to be accommodated in
the architecture. With this proposal we demonstrate that a standard
architecture for agent mobility capable of supporting several agent platforms
can be defined and implemented.


title: Asymmetric and Moving-Frame Approaches to Navier-Stokes Equations

abstract:
  In this paper, we introduce a method of imposing asymmetric conditions on the
velocity vector with respect to independent variables and a method of moving
frame for solving the three dimensional Navier-Stokes equations. Seven families
of non-steady rotating asymmetric solutions with various parameters are
obtained. In particular, one family of solutions blow up at any point on a
moving plane with a line deleted, which may be used to study turbulence. Using
Fourier expansion and two families of our solutions, one can obtain
discontinuous solutions that may be useful in study of shock waves. Another
family of solutions are partially cylindrical invariant, contain two parameter
functions of $t$ and structurally depend on two arbitrary polynomials, which
may be used to describe incompressible fluid in a nozzle. Most of our solutions
are globally analytic with respect to spacial variables.

categories: physics.flu-dyn math-ph math.AP math.MP nlin.SI


title:
Optimal H2 order-one reduction by solving eigenproblems for polynomial
  equations

abstract:
  A method is given for solving an optimal H2 approximation problem for SISO
linear time-invariant stable systems. The method, based on constructive
algebra, guarantees that the global optimum is found; it does not involve any
gradient-based search, and hence avoids the usual problems of local minima. We
examine mostly the case when the model order is reduced by one, and when the
original system has distinct poles. This case exhibits special structure which
allows us to provide a complete solution. The problem is converted into linear
algebra by exhibiting a finite-dimensional basis for a certain space, and can
then be solved by eigenvalue calculations, following the methods developed by
Stetter and Moeller. The use of Buchberger's algorithm is avoided by writing
the first-order optimality conditions in a special form, from which a Groebner
basis is immediately available. Compared with our previous work the method
presented here has much smaller time and memory requirements, and can therefore
be applied to systems of significantly higher McMillan degree. In addition,
some hypotheses which were required in the previous work have been removed.
Some examples are included.


title: Positions of Point-Nodes in Borocarbide Superconductor YNi2B2C

abstract:
  To determine the superconducting gap function of YNi2B2C, we calculate the
local density of states (LDOS) around a single vortex core with the use of
Eilenberger theory and the band structure calculated by local density
approximation assuming various gap structures with point-nodes at different
positions. We also calculate the angular-dependent heat capacity in the vortex
state on the basis of the Doppler-Shift method. Comparing our results with the
STM/STS experiment, the angular-dependent heat capacity and thermal
conductivity, we propose the gap-structure of YNi2B2C, which has the
point-nodes and gap minima along <110>. Our gap-structure is consistent with
all results of angular-resolved experiments.


title: New Algebraic Approaches to Classical Boundary Layer Problems

abstract:
  In this paper, we use various ansatzes with undetermined functions and the
technique of moving frame to find solutions with parameter functions modulo the
Lie point symmetries for the classical non-steady boundary layer problems.
These parameter functions enable one to find the solutions of some related
practical models and boundary value problems.


title: Young massive star clusters in the era of the Hubble Space Telescope

abstract:
  The Hubble Space Telescope (HST) has been instrumental in the discovery of
large numbers of extragalactic young massive star clusters (YMCs), often
assumed to be proto-globular clusters (GCs). As a consequence, the field of YMC
formation and evolution is thriving, generating major breakthroughs as well as
controversies on annual (or shorter) time-scales. Here, I review the long-term
survival chances of YMCs, hallmarks of intense starburst episodes often
associated with violent galaxy interactions. In the absence of significant
external perturbations, the key factor determining a cluster's long-term
survival chances is the shape of its stellar initial mass function (IMF). It
is, however, not straightforward to assess the IMF shape in unresolved
extragalactic YMCs. I also discuss the latest progress in worldwide efforts to
better understand the evolution of entire cluster populations, predominantly
based on HST observations, and conclude that there is an increasing body of
evidence that GC formation appears to be continuing until today; their
long-term evolution crucially depends on their environmental conditions,
however.


title: Recent developments in small-x physics

abstract:
  Recent theoretical progress in understanding high-energy scattering beyond
the mean field approximation is reviewed. The role of Lorentz invariance and
pomeron loops in the evolution, the relation between high-energy QCD and
statistical physics and results for the saturation momentum and the scattering
amplitude are discussed.


title: Exclusive rho0 electroproduction

abstract:
  Exclusive rho0 electroproduction at HERA has been studied with the ZEUS
detector, using 120 pb{-1} integrated luminosity, in the kinematic range of
photon virtuality of 2 < Q2 < 160 GeV2, and gamma* p center-of-mass energy of
32 < W < 180 GeV. The results include the Q2 and W dependence of the gamma* p
--> rho0 p cross section and the distribution of the squared-four-momentum
transfer to the proton, t. Also included is the ratio of longitudinal to
transverse gamma* p cross section as a function of Q2, W and t. Finally, the
effective Pomeron trajectory was extracted. The results are compared to various
theoretical predictions, none of which are able to reproduce all the features
of the data.


title: Contributions of Issai Schur to Analysis

abstract:
  The name Schur is associated with many terms and concepts that are widely
used in a number of diverse fields of mathematics and engineering. This survey
article focuses on Schur's work in analysis. Here too, Schur's name is
commonplace: The Schur test and Schur-Hadamard multipliers (in the study of
estimates for Hermitian forms), Schur convexity, Schur complements, Schur's
results in summation theory for sequences (in particular, the fundamental
Kojima-Schur theorem), the Schur-Cohn test, the Schur algorithm, Schur
parameters and the Schur interpolation problem for functions that are
holomorphic and bounded by one in the unit disk. In this survey, we discuss all
of the above mentioned topics and then some, as well as some of the
generalizations that they inspired. There are nine sections of text, each of
which is devoted to a separate theme based on Schur's work. Each of these
sections has an independent bibliography. There is very little overlap. A tenth
section presents a list of the papers of Schur that focus on topics that are
commonly considered to be analysis. We begin with a review of Schur's less
familiar papers on the theory of commuting differential operators.


title: Shock heating by FR I radio sources in galaxy clusters

abstract:
  Feedback by active galactic nuclei (AGN) is frequently invoked to explain the
cut-off of the galaxy luminosity function at the bright end and the absence of
cooling flows in galaxy clusters. Meanwhile, there are recent observations of
shock fronts around radio-loud AGN. Using realistic 3D simulations of jets in a
galaxy cluster, we address the question what fraction of the energy of active
galactic nuclei is dissipated in shocks. We find that weak shocks that
encompass the AGN have Mach numbers of 1.1-1.2 and dissipate at least 2% of the
mechanical luminosity of the AGN. In a realistic cluster medium, even a
continuous jet can lead to multiple shock structures, which may lead to an
overestimate of the AGN duty cycles inferred from the spatial distribution of
waves.


title:
Stability of coreless vortices in ferromagnetic spinor Bose-Einstein
  condensates

abstract:
  We study the energetic and dynamic stability of coreless vortices in
nonrotated spin-1 Bose-Einstein condensates, trapped with a three-dimensional
optical potential and a Ioffe-Pritchard field. The stability of stationary
vortex states is investigated by solving the corresponding Bogoliubov
equations. We show that the quasiparticle excitations corresponding to
axisymmetric stationary states can be taken to be eigenstates of angular
momentum in the axial direction. Our results show that coreless vortex states
can occur as local or global minima of the condensate energy or become
energetically or dynamically unstable depending on the parameters of the
Ioffe-Pritchard field. The experimentally most relevant coreless vortex state
containing a doubly quantized vortex in one of the hyperfine spin components
turned out to have very non-trivial stability regions, and especially a
quasiperiodic dynamic instability region which corresponds to splitting of the
doubly quantized vortex.


title:
Simulation study of the two-dimensional Burridge-Knopoff model of
  earthquakes

abstract:
  Spatiotemporal correlations of the two-dimensional spring-block
(Burridge-Knopoff) model of earthquakes are extensively studied by means of
numerical computer simulations. The model is found to exhibit either
``subcritical'' or ``supercritical'' behavior, depending on the values of the
model parameters. Transition between these regimes is either continuous or
discontinuous. Seismic events in the ``subcritical'' regime and those in the
``supercritical'' regime at larger magnitudes exhibit universal scaling
properties. In the ``supercritical'' regime, eminent spatiotemporal
correlations, {\it e.g.}, remarkable growth of seismic activity preceding the
mainshock, arise in earthquake occurrence, whereas such spatiotemporal
correlations are significantly suppressed in the ``subcritical'' regime.
Seismic activity is generically suppressed just before the mainshock in a close
vicinity of the epicenter of the upcoming event while it remains to be active
in the surroundings (the Mogi doughnut). It is also observed that, before and
after the mainshock, the apparent $B$-value of the magnitude distribution
decreases or increases in the ``supercritical'' or ``subcritical'' regimes,
respectively. Such distinct precursory phenomena may open a way to the
prediction of the upcoming large event.


title:
Time-Dependent Pseudo-Hermitian Hamiltonians Defining a Unitary Quantum
  System and Uniqueness of the Metric Operator

abstract:
  The quantum measurement axiom dictates that physical observables and in
particular the Hamiltonian must be diagonalizable and have a real spectrum. For
a time-independent Hamiltonian (with a discrete spectrum) these conditions
ensure the existence of a positive-definite inner product that renders the
Hamiltonian self-adjoint. Unlike for a time-independent Hamiltonian, this does
not imply the unitarity of the Schroedinger time-evolution for a general
time-dependent Hamiltonian. We give an additional necessary and sufficient
condition for the unitarity of time-evolution. In particular, we obtain the
general form of a two-level Hamiltonian that fulfils this condition. We show
that this condition is geometrical in nature and that it implies the reality of
the adiabatic geometric phases. We also address the problem of the uniqueness
of the metric operator.


title:
COSMOSOMAS Observations of the CMB and Galactic Foregrounds at 11 GHz:
  Evidence for anomalous microwave emission at high Galactic Latitude

abstract:
  We present observations with the new 11 GHz radiometer of the COSMOSOMAS
experiment at the Teide Observatory (Tenerife). The sky region between 0 deg <=
RA <= 360 deg and 26 deg <= DEC 49 deg (ca. 6500 square degrees) was observed
with an angular resolution of 0.9 deg. Two orthogonal independent channels in
the receiving system measured total power signals from linear polarizations
with a 2 GHz bandwidth. Maps with an average sensitivity of 50 microK per beam
have been obtained for each channel. At high Galactic latitude (|b|>30deg) the
11 GHz data are found to contain the expected cosmic microwave background as
well as extragalactic radiosources, galactic synchrotron and free-free
emission, and a dust-correlated component which is very likely of galactic
origin. At the angular scales allowed by the window function of the experiment,
the dust-correlated component presents an amplitude \Delta T aprox. 9-13 microK
while the CMB signal is of order 27 microK. The spectral behaviour of the
dust-correlated signal is examined in the light of previous COSMOSOMAS data at
13-17 GHz and WMAP data at 22-94 GHz in the same sky region. We detect a
flattening in the spectral index of this signal below 20 GHz which rules out
synchrotron radiation as being responsible for the emission. This anomalous
dust emission can be described by a combination of free-free emission and
spinning dust models with a flux density peaking around 20 GHz.


title: Quelques math\'ematiques de la cryptographie \`a cl\'es publiques

abstract:
  I present examples of mathematical objects that are of interest for public
key cryptography. Text for the Journ\'ee Annuelle 2007 of the SMF.


title: Derivative expansion of the heat kernel in curved space

abstract:
  The heat kernel in curved space-time is computed to fourth order in a strict
expansion in the number of covariant derivatives. The computation is made for
arbitrary non abelian gauge and scalar fields and for the Riemann connection in
the coordinate sector. The expressions obtained hold for arbitrary tensor
representations of the matter field. Complete results are presented for the
diagonal matrix elements and for the trace of the heat kernel operator. In
addition, Chan's formula is extended to curved space-time. As a byproduct, the
bosonic effective action is also obtained to fourth order.


title: A mathematical model for a copolymer in an emulsion

abstract:
  In this paper we review some recent results, obtained jointly with Stu
Whittington, for a mathematical model describing a copolymer in an emulsion.
The copolymer consists of hydrophobic and hydrophilic monomers, concatenated
randomly with equal density. The emulsion consists of large blocks of oil and
water, arranged in a percolation-type fashion. To make the model mathematically
tractable, the copolymer is allowed to enter and exit a neighboring pair of
blocks only at diagonally opposite corners. The energy of the copolymer in the
emulsion is minus $\alpha$ times the number of hydrophobic monomers in oil
minus $\beta$ times the number of hydrophilic monomers in water. Without loss
of generality we may assume that the interaction parameters are restricted to
the cone $\{(\alpha,\beta)\in \mathbb{R}^2\colon |\beta|\leq\alpha\}$.
  We show that the phase diagram has two regimes: (1) in the supercritical
regime where the oil blocks percolate, there is a single critical curve in the
cone separating a localized and a delocalized phase; (2) in the subcritical
regime where the oil blocks do not percolate, there are three critical curves
in the cone separating two localized phases and two delocalized phases, and
meeting at two tricritical points. The different phases are characterized by
different behavior of the copolymer inside the four neighboring pairs of
blocks.


title: Topological Zero-Thickness Cosmic Strings

abstract:
  In this paper, based on the gauge potential decomposition and the
$\phi-$mapping theories, we study the topological structures and properties of
the cosmic strings that arise in the Abelian-Higgs gauge theory in the
zero-thickness limit. After a detailed discussion, we conclude that the
topological tensor current introduced in our model is a better and more basic
starting point than the generally used Nambu-Goto effective action for studying
cosmic strings.


title:
Spectral density of phase noise inter-laboratory comparison final
  results

abstract:
  This paper reports main results of the phase noise comparison that has been
performed between october 2005 and december 2006, using two oscillators at 5
and 100 MHz and un DRO at 3.5 GHz. The problem is not to compare the
performances of several oscillators, but to compare and to make an evaluation
of the uncertainties, and of course the resolution and the reproducibility of
the measurements. This comparison allow us to determine the ability to get
various systems traceable together in order to increase the trust that one can
have in phase noise measurements.


title:
Homotopy classes of total foliations and bi-contact structures on
  three-manifolds

abstract:
  On every compact and orientable three-manifold, we construct total foliations
(three codimension 1 foliations that are transverse at every point). This
construction can be performed on any homotopy class of plane fields with
vanishing Euler class.
  As a corollary we obtain similar results on bi-contact structures.


title: Multiplicities and $J/\psi$ suppression at LHC energies

abstract:
  We present our predictions on multiplicities and $J/\psi$ suppression at LHC
energies. Our results take into account shadowing effects in the initial state
and final state interactions with the hot medium. We obtain 1800 charged
particles at LHC and the $J/\psi$ suppression increases by a factor 5 to 6
compared to RHIC.


title:
Magnetic excitations in the spin-trimer compounds Ca3Cu3-xNix(PO4)4
  (x=0,1,2)

abstract:
  Inelastic neutron scattering experiments were performed for the spin-trimer
compounds Ca3Cu3-xNix(PO4)4 (x=0,1,2) in order to study the dynamic magnetic
properties. The observed excitations can be associated with transitions between
the low-lying electronic states of linear Cu-Cu-Cu, Cu-Cu-Ni, and Ni-Cu-Ni
trimers which are the basic constituents of the title compounds. The exchange
interactions within the trimers are well described by the Heisenberg model with
dominant antiferromagnetic nearest-neighbor interactions J. For x=0 we find
JCu-Cu=-4.74(2) meV which is enhanced for x=1 to JCu-Cu=-4.92(6) meV. For x=1
and x=2 we find JCu-Ni=-0.85(10) meV and an axial single-ion anisotropy
parameter DNi=-0.7(1) meV. While the x=0 and x=1 compounds do not exhibit
long-range magnetic ordering down to 1 K, the x=2 compound shows
antiferromagnetic ordering below TN=20 K, which is compatible with the
molecular-field parameter 0.63(12) meV derived by neutron spectroscopy.


title:
Magnetodielectric effect and optic soft mode behaviour in quantum
  paraelectric EuTiO3 ceramics

abstract:
  Infrared reflectivity and time-domain terahertz transmission spectra of
EuTiO3 ceramics revealed a polar optic phonon at 6 - 300K, whose softening is
fully responsible for the recently observed quantum paraelectric behaviour.
Even if our EuTiO3 ceramics show lower permittivity than the single crystal due
to a reduced density and/or small amount of secondary pyrochlore Eu2Ti2O7
phase, we confirmed the magnetic field dependence of the permittivity, also
slightly smaller than in single crystal. Attempt to reveal the soft phonon
dependence at 1.8K on the magnetic field up to 13T remained below the accuracy
of our infrared reflectivity experiment.


title: Slave boson theory of the extended Falicov-Kimball model

abstract:
  The extended Falicov-Kimball model, with both an on-site hybridization
potential and dispersive narrow band, is examined within the saddle-point
approximation to the Kotliar-Ruckenstein slave boson theory. We first set the
hybridization potential to zero and find that the phase diagram depends
strongly upon the orbital structure: for degenerate orbitals, a
correlated-insulating state is found at sufficiently strong interaction
strengths, whereas a finite orbital energy difference can lead to discontinuous
valence transitions. The obtained phase diagram is very sensitive to the
presence of a finite hybridization potential. As in Hartree-Fock theory, we
find an enhancement of the hybridization by the inter-orbital Coulomb
repulsion. The more precise treatment of correlation effects, however, leads to
large deviations from the Hartree-Fock results. In the limit of vanishing
hybridization an excitonic insulator state is only found when the orbitals are
degenerate, which restricts this phase to a much smaller parameter space than
in other available mean-field theories.


title:
Mapping of spin lifetimes to electronic states in n-type GaAs near the
  metal-insulator transition

abstract:
  The longest spin lifetimes in bulk n-GaAs exceed 100 ns for doping
concentrations near the metal-insulator transition (J.M. Kikkawa, D.D.
Awschalom, Phys. Rev. Lett. 80, 4313 (1998)). The respective electronic states
have yet not been identified. We therefore investigate the energy dependence of
spin lifetimes in n-GaAs by time-resolved Kerr rotation. Spin lifetimes vary by
three orders of magnitude as a function of energy when occupying donor and
conduction band states. The longest spin lifetimes (>100 ns) are assigned to
delocalized donor band states, while conduction band states exhibit shorter
spin lifetimes. The occupation of localized donor band states is identified by
short spin lifetimes (~300 ps) and a distinct Overhauser shift due to dynamic
nuclear polarization.


title:
The impact of accretion disk winds on the X-ray spectrum of AGN: Part 1
  - XSCORT

abstract:
  (abridged) The accretion disk in AGN is expected to produce strong outflows,
in particular a UV-line driven wind. Despite providing a good fit to the data,
current spectral models of the X-ray spectrum of AGN observed through an
accretion disk wind are ad-hoc in their treatment of the properties of the wind
material. In order to address these limitations we adopt a numerical
computation method that links a series of radiative transfer calculations,
incorporating the effect of a global velocity field in a self-consistent manner
(XSCORT). We present a series of example spectra from the XSCORT code that
allow us to examine the shape of AGN X-ray spectra seen through a wind, for a
range of velocity and density distributions, total column densities and initial
ionization parameters. These detailed spectral models clearly show considerable
complexity and structure that is strongly affected by all these factors. The
presence of sharp features in the XSCORT spectra contrasts strongly with both
the previous models and with the smooth nature of the observed X-ray spectra of
AGN with soft X-ray excesses, demonstrating that accretion disk winds are
unlikely to be the origin of this mysterious spectral feature. The most
significant parameter affecting the presence of the sharp features in the
models is the terminal velocity of the wind. Increasing the terminal velocity
of the absorbing material to ~c, and hence dramatically increasing the velocity
dispersion across the wind, could potentially remove these features resulting
in a spectrum similar to the previous models. Such a fast moving outflow cannot
be associated with a radiatively driven accretion disk wind, however the
presence of a highly relativistic jet may provide an origin for such material.


title: On Transformation of Potapov's Fundamental Matrix Inequality

abstract:
  According to V.P.Potapov, a classical interpolation problem can be
reformulated in terms of a so-called Fundamental Matrix Inequality (FMI). To
show that every solution of the FMI satisfies the interpolation problem, we
usualy have to transform the FMI in some special way. In this paper the number
of of transformations of the FMI which come into play are motivated and
demonstrated by simple, but typical examples.


title:
Configuration Space Methods and Time Ordering for Scalar Propagators in
  (Anti and) de Sitter Spacetimes

abstract:
  In this master thesis a configuration space method presented by C. Dullemond
and E. van Beveren for computing all propagators of a scalar field (Wightman,
Hadamard and Schwinger functions,retarded, advanced and Feynman propagator) is
reviewed for four-dimensional Minkowski and Anti de Sitter spacetime AdS_4.
This method is then applied for AdS_d as well as de Sitter spacetime dS_d of
arbitrary dimension d, obtaining results in agreement with the literature. The
advantages of the method are that it needs neither mode summation nor analytic
continuation from euclidean time, while delivering the propagators above
including (i-epsilon)-prescription, plus as a nice bonus the conformal
dimension of a corresponding CFT field. General properties of the considered
spacetimes (namely various coordinate systems and their metrics, chordal
distances, relations between conformal dimensions \Delta and the mass m of the
scalar field, geodesics and the invariance of time ordering) are also examined
and compiled from various sources, providing an overview of geometrical
properties of AdS and dS spacetimes.


title:
Minimum Electrical and Thermal Conductivity of Graphene: A
  Quasiclassical Approach

abstract:
  We investigate the minimum conductivity of graphene within a quasiclassical
approach taking into account electron-hole coherence effects which stem from
the chiral nature of low energy excitations. Relying on an analytical solution
of the kinetic equation in the electron-hole coherent and incoherent cases we
study both the electrical and thermal conductivity whose relation fullfills
Wiedemann-Franz law. We found that the most of the previous findings based on
the Boltzmann equation are restricted to only high mobility samples where
electron-hole coherence effects are not sufficient.


title:
Super stellar clusters with a bimodal hydrodynamic solution: an
  Approximate Analytic Approach

abstract:
  We look for a simple analytic model to distinguish between stellar clusters
undergoing a bimodal hydrodynamic solution from those able to drive only a
stationary wind. Clusters in the bimodal regime undergo strong radiative
cooling within their densest inner regions, which results in the accumulation
of the matter injected by supernovae and stellar winds and eventually in the
formation of further stellar generations, while their outer regions sustain a
stationary wind. The analytic formulae are derived from the basic hydrodynamic
equations. Our main assumption, that the density at the star cluster surface
scales almost linearly with that at the stagnation radius, is based on results
from semi-analytic and full numerical calculations. The analytic formulation
allows for the determination of the threshold mechanical luminosity that
separates clusters evolving in either of the two solutions. It is possible to
fix the stagnation radius by simple analytic expressions and thus to determine
the fractions of the deposited matter that clusters evolving in the bimodal
regime blow out as a wind or recycle into further stellar generations.


title:
Determinant solution for the Totally Asymmetric Exclusion Process with
  parallel update II. Ring geometry

abstract:
  Using the Bethe ansatz we obtain the determinant expression for the time
dependent transition probabilities in the totally asymmetric exclusion process
with parallel update on a ring. Developing a method of summation over the roots
of Bethe equations based on the multidimensional analogue of the Cauchy residue
theorem, we construct the resolution of the identity operator, which allows us
to calculate the matrix elements of the evolution operator and its powers.
Representation of results in the form of an infinite series elucidates
connection to other results obtained for the ring geometry. As a byproduct we
also obtain the generating function of the joint probability distribution of
particle configurations and the total distance traveled by the particles.


title:
Inhomogeneous extragalactic magnetic fields and the second knee in the
  cosmic ray spectrum

abstract:
  Various experiments indicate the existence of a second knee around energy
E=3.10^{17} eV in the cosmic ray spectrum. This feature could be the signature
of the end of the galactic component and of the emergence of the extragalactic
one, provided that the latter cuts off at low energies. Recent analytical
calculations have shown that this cut-off could be a consequence of the
existence of extragalactic magnetic fields: low energy protons diffuse on
extragalactic magnetic fields and cannot reach the observer within a given
time. We study the influence of inhomogeneous magnetic fields on the magnetic
horizon, using a new semi-analytical propagation code. Our results indicate
that, at a fixed value of the volume averaged magnetic field <B>, the amplitude
of the low energy cut-off is mainly controled by the strength of magnetic
fields in the voids of the large scale structure distribution.


title: Unambiguous coherent state identification: Searching a quantum database

abstract:
  We consider an unambiguous identification of an unknown coherent state with
one of two unknown coherent reference states. Specifically, we consider two
modes of an electromagnetic field prepared in unknown coherent states alpha_1
and alpha_2, respectively. The third mode is prepared either in the state
alpha_1 or in the state alpha_2. The task is to identify (unambiguously) which
of the two modes are in the same state. We present a scheme consisting of three
beamsplitters capable to perform this task. Although we don't prove the
optimality, we show that the performance of the proposed setup is better than
the generalization of the optimal measurement known for a finite-dimensional
case. We show that a single beamsplitter is capable to perform an unambiguous
quantum state comparison for coherent states optimally. Finally we propose an
experimental setup consisting of 2N-1 beamsplitters for unambiguous
identification among N unknown coherent states. This setup can be considered as
a search in a quantum database. The elements of the database are unknown
coherent states encoded in different modes of an electromagnetic field. The
task is to specify the two modes that are excited in the same, though unknown,
coherent state.


title: Stability and Negative Tensions in 6D Brane Worlds

abstract:
  We investigate the dynamical stability of warped, axially symmetric
compactifications in anomaly free 6D gauged supergravity. The solutions have
conical defects, which we source by 3-branes placed on orbifold fixed points,
and a smooth limit to the classic sphere-monopole compactification. Like for
the sphere, the extra fields that are generically required by anomaly freedom
are especially relevant for stability. With positive tension branes only, there
is a strict stability criterion (identical to the sphere case) on the charges
present under the monopole background. Thus brane world models with positive
tensions can be embedded into anomaly free theories in only a few ways.
Meanwhile, surprisingly, in the presence of a negative tension brane the
stability criteria can be relaxed. We also describe in detail the geometries
induced by negative tension codimension two branes.


title: How to find sterile neutrinos ?

abstract:
  We describe an extention of the Standard Model (the $\nu$MSM) by three light
singlet Majorana fermions -- sterile neutrinos, which allows to address
simultaneously the problem of neutrino oscillations and the problems of dark
matter and baryon asymmetry of the Universe. We discuss the ways these new
particles can be searched for in astrophysical, laboratory, and accelerator
experiments.


title:
Thermal noise influences fluid flow in thin films during spinodal
  dewetting

abstract:
  Experiments on dewetting thin polymer films confirm the theoretical
prediction that thermal noise can strongly influence characteristic time-scales
of fluid flow and cause coarsening of typical length scales. Comparing the
experiments with deterministic simulations, we show that the Navier-Stokes
equation has to be extended by a conserved bulk noise term to accomplish the
observed spectrum of capillary waves. Due to thermal fluctuations the spectrum
changes from an exponential to a power law decay for large wavevectors. Also
the time evolution of the typical wavevector of unstable perturbations exhibits
noise induced coarsening that is absent in deterministic hydrodynamic flow.


title:
An Abstract Interpolation Problem and the Extension Theory of Hermitian
  Operators

abstract:
  The algebraic structure of V.P. Potapov's Fundamental Matrix Inequality (FMI)
is discussed and its interpolation meaning is analyzed. Functional model spaces
are involved. A general Abstract Interpolation Problem is formulated which
seems to cover all the classical and recent problems in the field and the
solution set of this problem is described using the Arov--Grossman formula. The
extension theory of isometric operators is the proper language for treating
interpolation problems of this type.


title:
Non-local correlations in metals close to a charge order insulator
  transition

abstract:
  The charge ordering transition induced by the nearest-neighbor Coulomb
repulsion, V, in the 1/4-filled extended Hubbard model is investigated using
Cellular Dynamical Mean-Field Theory. We find a transition to a strongly
renormalized charge ordered Fermi liquid at VCO and a metal-to-insulator
transition at VMI>VCO. Short range antiferromagnetism occurs concomitanly with
the CO transition. Approaching the charge ordered insulator the Fermi surface
deforms and the scattering rate of electrons develops momentum dependence on
the Fermi surface.


title:
Search for a Standard Model Higgs Boson in CMS via Vector Boson Fusion
  in the H->WW->l\nu l\nu Channel

abstract:
  We present the potential for discovering the Standard Model Higgs boson
produced by the vector-boson fusion mechanism. We considered the decay of Higgs
bosons into the W+W- final state, with both W-bosons subsequently decaying
leptonically. The main background is ttbar with one or more jets produced. This
study is based on a full simulation of the CMS detector, and up-to-date
reconstruction codes. The result is that a signal of 5 sigma significance can
be obtained with an integrated luminosity of 12-72 1/fb for Higgs boson masses
between 130-200 GeV. In addition, the major background can be measured directly
to 7% from the data with an integrated luminosity of 30 1/fb. In this study, we
also suggested a method to obtain information in Higgs mass using the
transverse mass distributions.


title: Spacetime Lagrangian Formulation of Barbero-Immirzi Gravity

abstract:
  We shall here discuss a new spacetime gauge-covariant Lagrangian formulation
of General Relativity by means of the Barbero-Immirzi SU(2)-connection on
spacetime. To the best of our knowledge the Lagrangian based on SU(2) spacetime
fields seems to appear here for the first time.


title:
Astrometry with "Carte du Ciel" plates, San Fernando zone. I.
  Digitization and measurement using a flatbed scanner

abstract:
  We present an original method of digitizing and astrometrically reducing
"Carte du Ciel" plate material using an inexpensive flatbed scanner, to
demonstrate that for this material there is an alternative to more specialized
measuring machines that are very few in number and thus not readily available.
The sample of plates chosen to develop this method are original "Carte du Ciel"
plates of the San Fernando zone, photographic material with a mean epoch
1903.6, and a limiting photographic magnitude ~14.5, covering the declination
range of -10 < dec < -2. Digitization has been made using a commercial flatbed
scanner, demonstrating the internal precision that can be attained with such a
device. A variety of post-scan corrections are shown to be necessary. In
particular, the large distortion introduced by the non-uniform action of the
scanner is modelled using multiple scans of each plate. We also tackle the
specific problems associated with the triple-exposure images on some plates and
the grid lines present on all. The final measures are reduced to celestial
coordinates using the Tycho-2 Catalogue. The internal precision obtained over a
single plate, 3microns ~ 0.18" in each axis, is comparable to what is realized
with similar plate material using slower, less affordable, and less widely
available conventional measuring machines, such as a PDS microdensitometer. The
accuracy attained over large multi-plate areas, employing an overlapping plate
technique, is estimated at 0.2".


title: On the Theory of Matrix Valued Functions Belonging to the Smirnov Class

abstract:
  A theory of matrix-valued functions from the matricial Smirnov class ${\goth
N}_n^+({\Bbb D})$ is systematically developed. In particular, the maximum
principle of
  V.I.Smirnov, inner-outer factorization, the Smirnov-Beurling characterization
of outer functions and an analogue of Frostman's theorem are presented for
matrix-valued functions from the Smirnov class ${\goth N}_n^+({\Bbb D})$.
  We also consider a family $F_{\lambda} =F-\lambda I$ of functions belonging
to the matricial Smirnov class which is indexed by a complex parameter
$\lambda$. We show that with the exception of a ''very small'' set of such
$\lambda$ the corresponding inner factor in the inner-outer factorization of
the function $F_{\lambda}$ is a Blaschke-Potapov product. The main goal of this
paper is to provide users of analytic matrix-function theory with a standard
source for references related to the matricial Smirnov class.


title:
The Curvature of F_2^p(x, Q^2) as a Probe of Perturbative QCD Evolutions
  in the small-x Region

abstract:
  Perturbative NLO and NNLO QCD evolutions of parton distributions are studied,
in particular in the (very) small-x region, where they are in very good
agreement with all recent precision measurements of F_2^p(x,Q^2). These
predictions turn out to be also rather insensitive to the specific choice of
the factorization scheme (MS or DIS). A characteristic feature of perturbative
QCD evolutions is a positive curvature of F_2^p which increases as x decreases.
This perturbatively stable prediction provides a sensitive test of the range of
validity of perturbative QCD.


title:
Ultra-cold atoms in an optical cavity: two-mode laser locking to the
  cavity avoiding radiation pressure

abstract:
  The combination of ultra-cold atomic clouds with the light fields of optical
cavities provides a powerful model system for the development of new types of
laser cooling and for studying cooperative phenomena. These experiments
critically depend on the precise tuning of an incident pump laser with respect
to a cavity resonance. Here, we present a simple and reliable experimental
tuning scheme based on a two-mode laser spectrometer. The scheme uses a first
laser for probing higher-order transversal modes of the cavity having an
intensity minimum near the cavity's optical axis, where the atoms are confined
by a magnetic trap. In this way the cavity resonance is observed without
exposing the atoms to unwanted radiation pressure. A second laser, which is
phase-locked to the first one and tuned close to a fundamental cavity mode
drives the coherent atom-field dynamics.


title: Survival Probabilities for N-ary Subtrees on a Galton-Watson Family Tree

abstract:
  The family tree of a Galton-Watson branching process may contain N-ary
subtrees, i.e. subtrees whose vertices have at least N>0 children. For family
trees without infinite N-ary subtrees, we study how fast N-ary subtrees of
height t disappear as t goes to infinity.


title:
Quantum dynamics of N-methylacetamide studied by the vibrational
  configuration interaction method

abstract:
  Vibrational energy transfer of the amide I mode of N-methylacetamide (NMA) is
studied theoretically using the vibrational configuration interaction method. A
quartic force field of NMA is constructed at the B3LYP/6-31G+(d) level of
theory and its accuarcy is checked by comparing the resulting anharmonic
frequencies with available theoretical and experimental values. Quantum
dynamics calculations for the amide I mode excitation clarify the dominant
energy transfer pathways, which sensitively depend on the anharmonic couplings
among vibrational modes. A ratio of the anharmonic coupling to the frequency
mismatch is employed to predict and interpret the dominant energy flow
pathways.


title:
Spatial correlations in the dynamics of glassforming liquids:
  Experimental determination of their temperature dependence

abstract:
  We use recently introduced three-point dynamic susceptibilities to obtain an
experimental determination of the temperature evolution of the number of
molecules, N_corr, that are dynamically correlated during the structural
relaxation of supercooled liquids. We first discuss in detail the physical
content of three-point functions that relate the sensitivity of the averaged
two-time dynamics to external control parameters (such as temperature or
density), as well as their connection to the more standard four-point dynamic
susceptibility associated with dynamical heterogeneities. We then demonstrate
that these functions can be experimentally determined with a good precision. We
gather available data to obtain the temperature dependence of N_corr for a
large number of supercooled liquids over a wide range of relaxation timescales
from the glass transition up to the onset of slow dynamics. We find that N_corr
systematically grows when approaching the glass transition. It does so in a
modest manner close to the glass transition, which is consistent with an
activation-based picture of the dynamics in glassforming materials. For higher
temperatures, there appears to be a regime where N_corr behaves as a power-law
of the relaxation time. Finally, we find that the dynamic response to density,
while being smaller than the dynamic response to temperature, behaves
similarly, in agreement with theoretical expectations.


title: Nagata's embedding theorem

abstract:
  In 1962-63, M. Nagata showed that an abstract variety could be embedded into
a complete variety. Later, P. Deligne translated Nagata's proof into the
language of schemes, but did not publish his notes. This paper, which is to
appear as an appendix in a forthcoming book, gives an elaboration of Deligne's
notes. It also contains some complementary results on extending divisors and
vector sheaves to suitable completions.


title:
Computational investigations into the orgins of 'short term' biochemical
  memory in T cell activation

abstract:
  Recent studies have reported that T cells can integrate signals between
interrupted encounters with Antigen Presenting Cells (APCs) in such a way that
the process of signal integration exhibits a form of memory. Here, we carry out
a computational study using a simple mathematical model of T cell activation to
investigate the ramifications of interrupted T cell-APC contacts on signal
integration. We consider several mechanisms of how signal integration at these
time scales may be achieved and conclude that feedback control of immediate
early gene products (IEGs) appears to be a highly plausible mechanism that
allows for effective signal integration and cytokine production from multiple
exposures to APCs. Analysis of these computer simulations provides an
experimental roadmap involving several testable predictions.

categories: q-bio.MN physics.bio-ph q-bio.CB q-bio.SC


title:
Observations of X-rays and Thermal Dust Emission from the Supernova
  Remnant Kes 75

abstract:
  We present Spitzer Space Telescope and Chandra X-ray Observatory observations
of the composite Galactic supernova remnant Kes 75 (G29.7-0.3). We use the
detected flux at 24 microns and hot gas parameters from fitting spectra from
new, deep X-ray observations to constrain models of dust emission, obtaining a
dust-to-gas mass ratio M_dust/M_gas ~0.001. We find that a two-component
thermal model, nominally representing shocked swept-up interstellar or
circumstellar material and reverse-shocked ejecta, adequately fits the X-ray
spectrum, albeit with somewhat high implied densities for both components. We
surmise that this model implies a Wolf-Rayet progenitor for the remnant. We
also present infrared flux upper limits for the central pulsar wind nebula.


title: Bispinor Formulation of Spin 3/2 Field Theory

abstract:
  In this paper, we investigate an alternative formulation for spin 3/2 field
equation. First we will review equation of motion of Dirac and Maxwell, and
then construct the equation for spin 3/2 in the similar fashion. Our method
actually a generalization of relativistic equation of motion based on spin
operator and Hamiltonian similar to Dirac and Maxwell equation in ref. [1] pp.
50. Furthermore, we could not bring the equation to the Klein Gordon limit for
every wave function component in spin 3/2 formalism.


title:
Holographic formation of large area split-ring arrays for magnetic
  metamaterials

abstract:
  We theoretically demonstrate the formation of different kinds of
two-dimensional split-ring arrays in both triangular and square lattices by
one-step holographic interference. The slit width of the split-ring can be
adjusted by proper polarization configurations. The dimension of the rings can
be adjusted easily by using different wavelengths for interference, so the
resonant frequency of the split-rings can be obtained in a wide range. Our
theory is also proved in experiment. Our work would extend the application of
holographic lithography to the fabrication of magnetic metamaterials.


title:
Stellar Content and Recent Star Formation History of the Local Group
  Dwarf Irregular Galaxy IC1613

abstract:
  We present resolved-star VI photometry of the Local Group dwarf irregular
galaxy IC1613 reaching I~23.5, obtained with the wide-field camera at the 2.5m
Isaac Newton Telescope. A fit to the stellar density distribution shows an
exponential profile of scale length 2.9' +/- 0.1 and gives a central surface
brightness mu_V,0 = 22.7 +/- 0.6. The significant number of red giant branch
(RGB) stars present in the outer part of our images (r > 16.5') indicates that
the galaxy is actually more extended than previously estimated. A comparison of
the color-magnitude diagrams (CMDs) as a function of galactocentric distance
shows a clear gradient in the age of its population, the scale length
increasing with age, while we find no evidence of a metallicity gradient from
the width of the RGB. We present quantitative results of the recent star
formation history from a synthetic CMD analysis using IAC-STAR. We find a mean
star formation rate of (1.6 +/- 0.8) x 10^{-3} Mo/yr/kpc^2 in the central r <
2.5' for the last 300 Myr.


title: Velocity Profiles in the Solar Corona from Multi-Instrument Observations

abstract:
  We present a method to derive outflow velocities in the solar corona using
different data sets including solar wind mass flux coming from the SWAN/SOHO
instrument, electron density values from LASCO-C2 and interplanetary solar wind
velocities derived from ground-based Interplanetary Scintillation Observations
(IPS).
  In a first step, we combine the LASCO electron densities at 6 solar radii and
the IPS velocities, and compare the product to the SWAN mass fluxes. It is
found that this product represents the actual mass flux at 6 solar radii for
the fast wind, but not for the slow wind. In regions dominated by the slow
wind, the fluxes derived from SWAN are systematically smaller. This is
interpreted as a proof that the fast solar wind has reached its terminal
velocity at about 6 solar radii and expands with constant velocity beyond this
distance. On the contrary, the slow solar wind has reached only half of its
terminal value and is thus accelerated further out.
  In a second step, we combine the LASCO-C2 density profiles and the SWAN flux
data to derive velocity profiles in the corona between 2.5 and 6 solar radii.
Such profiles can be used to test models of the acceleration mechanism of the
fast solar wind.


title:
Approche variationnelle pour le calcul bay\'esien dans les probl\`emes
  inverses en imagerie

abstract:
  In a non supervised Bayesian estimation approach for inverse problems in
imaging systems, one tries to estimate jointly the unknown image pixels $\fb$
and the hyperparameters $\thetab$. This is, in general, done through the joint
posterior law $p(\fb,\thetab|\gb)$. The expression of this joint law is often
very complex and its exploration through sampling and computation of the point
estimators such as MAP and posterior means need either optimization of non
convex criteria or int\'egration of non Gaussian and multi variate probability
laws. In any of these cases, we need to do approximations. We had explored
before the possibilities of Laplace approximation and sampling by MCMC. In this
paper, we explore the possibility of approximating this joint law by a
separable one in $\fb$ and in $\thetab$. This gives the possibility of
developing iterative algorithms with more reasonable computational cost, in
particular, if the approximating laws are choosed in the exponential conjugate
families. The main objective of this paper is to give details of different
algorithms we obtain with different choices of these families.


title: How to disentangle two braided Hopf algebras

abstract: We show how to define the tensor product of two braided Hopf algebras.


title:
GRMHD/RMHD Simulations and Stability of Magnetized Spine-Sheath
  Relativistic Jets

abstract:
  A new general relativistic magnetohydrodynamics (GRMHD) code ``RAISHIN'' used
to simulate jet generation by rotating and non-rotating black holes with a
geometrically thin Keplarian accretion disk finds that the jet develops a
spine-sheath structure in the rotating black hole case. Spine-sheath structure
and strong magnetic fields significantly modify the Kelvin-Helmholtz (KH)
velocity shear driven instability. The RAISHIN code has been used in its
relativistic magnetohydrodynamic (RMHD) configuration to study the effects of
strong magnetic fields and weakly relativistic sheath motion, c/2, on the KH
instability associated with a relativistic, Lorentz factor equal 2.5, jet
spine-sheath interaction. In the simulations sound speeds up to c/1.7 and
Alfven wave speeds up to 0.56 c are considered. Numerical simulation results
are compared to theoretical predictions from a new normal mode analysis of the
RMHD equations. Increased stability of a weakly magnetized system resulting
from c/2 sheath speeds and stabilization of a strongly magnetized system
resulting from c/2 sheath speeds is found.


title:
Propagation of travelling waves in sub-excitable systems driven by noise
  and periodic forcing

abstract:
  It has been reported that traveling waves propagate periodically and stably
in sub-excitable systems driven by noise [Phys. Rev. Lett. \textbf{88}, 138301
(2002)]. As a further investigation, here we observe different types of
traveling waves under different noises and periodic forces, using a simplified
Oregonator model. Depending on different noises and periodic forces, we have
observed different types of wave propagation (or their disappearance).
Moreover, the reversal phenomena are observed in this system based on the
numerical experiments in the one-dimensional space. As an explanation, we
regard it as the effect of periodic forces. Thus, we give qualitative
explanations to how reversal phenomena stably appear, which seem to arise from
the mixing function of the periodic force and the noise. And the output period
and three velocities (the normal, the positive and the negative) of the
travelling waves are defined and their relationship with the periodic forces,
along with the types of waves, are also studied in sub-excitable system under a
fixed noise intensity.

categories: nlin.CD nlin.PS physics.flu-dyn physics.med-ph


title: Affine Buildings and Tropical Convexity

abstract:
  The notion of convexity in tropical geometry is closely related to notions of
convexity in the theory of affine buildings. We explore this relationship from
a combinatorial and computational perspective. Our results include a convex
hull algorithm for the Bruhat--Tits building of SL$_d(K)$ and techniques for
computing with apartments and membranes. While the original inspiration was the
work of Dress and Terhalle in phylogenetics, and of Faltings, Kapranov, Keel
and Tevelev in algebraic geometry, our tropical algorithms will also be
applicable to problems in other fields of mathematics.


title: Simple dynamic exchange-correlation kernel of the uniform electron gas

abstract:
  We propose a simple dynamic exchange-correlation kernel of the uniform
electron gas. We model the reduction of the electron-electron interaction due
to short-range exchange-correlation effects by introducing a
frequency-dependent error-function effective interaction. By imposing the
fulfillment of the compresibility and the third-frequency-moment sum rules, as
well as the correct asymptotic behavior at large wave vectors, we find an
accurate and simple dynamic exchange-correlation kernel that accurately
reproduces the wave-vector analysis and the imaginary-frequency analysis of the
correlation energy of the uniform electron gas.


title: On a problem of Duke-Erdos-Rodl on cycle-connected subgraphs

abstract:
  In this short note, we prove that for \beta < 1/5 every graph G with n
vertices and n^{2-\beta} edges contains a subgraph G' with at least
cn^{2-2\beta} edges such that every pair of edges in G' lie together on a cycle
of length at most 8. Moreover edges in G' which share a vertex lie together on
a cycle of length at most 6. This result is best possible up to the constant
factor and settles a conjecture of Duke, Erdos, and Rodl.


title:
Test of hadronic interaction models with data from the Pierre Auger
  Observatory

abstract:
  The Pierre Auger Observatory allows the measurement of both longitudinal
profiles and lateral particle distributions of high-energy showers. The former
trace the overall shower development, mainly of the electromagnetic component
close to the core where the latter reflect the particle densities in the tail
of the shower far away from the core and are sensitive to both the muonic and
electromagnetic components. Combining the two complementary measurements,
predictions of air shower simulations are tested. In particular the muon
component of the tank signals, which is sensitive to hadronic interactions at
high energy, is studied with several independent methods. Implications for the
simulation of hadronic interactions at ultra-high energy are discussed.


title: Spontaneous Symmetry Breaking and Decoherence in Superconductors

abstract:
  We show that superconductors have a thin spectrum associated with spontaneous
symmetry breaking similar to that of antiferromagnets, while still being in
full agreement with Elitzur's theorem, which forbids the spontaneous breaking
of local (gauge) symmetries. This thin spectrum in the superconductors consists
of in-gap states that are associated with the spontaneous breaking of a global
phase symmetry. In qubits based on mesoscopic superconducting devices, the
presence of the thin spectrum implies a maximum coherence time which is
proportional to the number of Cooper pairs in the device. Here we present the
detailed calculations leading up to these results and discuss the relation
between spontaneous symmetry breaking in superconductors and the Meissner
effect, the Anderson-Higgs mechanism and the Josephson effect. Whereas for the
Meissner effect a symmetry breaking of the phase of the superconductor is not
required, it is essential for the Josephson effect.